Denatured fuel ethanol compositions for blending with gasoline or diesel fuel for use as motor fuels

ABSTRACT

A denatured fuel ethanol composition for blending with fuels, including gasoline and diesel fuel. The composition includes an ethanol composition comprising at least 92 wt. % ethanol; and from 95 wppm to 1,000 wppm isopropanol; and at least 1.96 vol. % fuel denaturant.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.12/852,290, filed on Aug. 6, 2010, now U.S. Pat. No. 8,460,405, whichclaims priority to U.S. Provisional Application No. 61/300,815, filed onFeb. 2, 2010, and U.S. Provisional Application No. 61/332,696, filed onMay 7, 2010, U.S. Provisional Application No. 61/332,699, filed on May7, 2010; U.S. Provisional Application No. 61/332,728, filed on May 7,2010, and U.S. Provisional Application No. 61/346,344, filed on May 19,2010, and a continuation-in-part of U.S. application Ser. No.12/903,756, filed on Oct. 13, 2010, now U.S. Pat. No. 8,541,633, whichclaims priority to U.S. Provisional Application No. 61/332,726, filed onMay 7, 2010 and to U.S. Provisional Application No. 61/300,815, filed onFebruary 2, 2010, the entire contents and disclosures of which areincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to processes for producingand/or purifying ethanol for use in producing denatured fuel ethanoland, in particular, to denatured fuel ethanol compositions.

BACKGROUND OF THE INVENTION

Ethanol is conventionally produced from petrochemical feed stocks, suchas oil, natural gas, or coal, from feed stock intermediates, such assyngas, or from starchy materials or cellulose materials, such as cornor sugar cane. Conventional methods for producing ethanol frompetrochemical feed stocks, as well as from cellulose materials, includethe acid-catalyzed hydration of ethylene, methanol homologation, directalcohol synthesis, and Fischer-Tropsch synthesis. Instability inpetrochemical feed stock prices contributes to fluctuations in the costof conventionally produced ethanol, making the need for alternativesources of ethanol production all the greater when feed stock pricesrise. Starchy materials, as well as cellulose material, are converted toethanol by fermentation. However, fermentation is typically used forconsumer production of ethanol for fuels or consumption. In addition,fermentation of starchy or cellulose materials competes with foodsources and places restraints on the amount of ethanol that can beproduced for fuel use.

With regard to the use ethanol produced from fermentation, theInternational Monetary Fund observed in 2008 that such fuels accountedfor 1.5% of the global liquid fuels supply that year, but representednearly half the increase in food crop consumption, mainly due to the useof corn-based ethanol in the U.S. In 2011, 40% of the U.S. corn cropwill go into the motor fuel pool. Moreover, this fact has been said tohave played a role in the increase in food prices.

Anhydrous ethanol or substantially anhydrous ethanol is often preferredfor fuel applications. Anhydrous or substantially anhydrous ethanol,however, is often difficult to obtain from conventional hydrogenationand separation processes. For example, the ethanol and water produced inconventional hydrogenation reactions may form a binary azeotrope. Thisazeotrope contains about 95% ethanol and about 5% water. Because theboiling point of this azeotrope (78° C.) is just slightly below that ofpure ethanol (78.4° C.), an anhydrous or substantially anhydrous ethanolcomposition is difficult to obtain from a crude ethanol composition viasimple, conventional distillation.

Conventional ethanol compositions formed by the above-identifiedprocesses contain impurities which must be removed. For example, U.S.Pat. No. 5,488,185 utilizes a petrochemical feed stock and relates to anethene stream which contains ethane as an impurity or a propene streamwhich contains propane as an impurity that is hydrated with water vaporin the presence of a hydration catalyst to produce ethanol orisopropanol, respectively. After removal of the alcohol the gaseousproduct stream is subjected to adsorption, thereby producing anethene-enriched stream or a propene-enriched stream. The ethene-enrichedstream or the propene-enriched stream is recycled to the hydrationreactor.

U.S. Pat. Nos. 5,185,481 and 5,284,983 relate to conventionalfermentation methods for producing ethanol. The produced ethanolcompositions comprise impurities such as methanol, acetaldehyde,n-propanol, n-butanol, ethyl acetate, 3-methylbutanol, diethyl ether,acetone, secondary butanol, and crotonaldehyde. These references alsodisclose separation methods for treating the crude ethanol aqueoussolution with an extracting solvent comprising carbon dioxide in aliquid state or carbon dioxide in a super-critical state.

U.S. Pat. Nos. 5,445,716; 5,800,681; and 5,415,741 relate to separationmethods for mixtures of ethanol and isopropanol. Ethanol is difficult toseparate from isopropanol by conventional distillation or rectificationbecause of the proximity of their boiling points. Ethanol can be readilyseparated from isopropanol by extractive distillation. Effectiveextractive agents are dipentene, anisole, and ethyl benzene. Themixtures in these references, comprise a significant amount ofisopropanol, e.g., at least 21.5 wt. % isopropanol.

Also, U.S. Pat. No. 5,858,031 relates to a method for enhancing thevisibility of a flame produced during free-burning of an aqueousalcohol-based fuel composition in air. The fuel includes betweenapproximately 10% and 30% by volume of water, and between approximately70% and 90% by volume of a mixture of alcohols including ethanol andisopropanol, the ethanol constituting between approximately 24% and 83%by volume of the fuel composition. The method includes providing anamount of isopropanol ranging between approximately 7% and 60% by volumeof the fuel composition, in which the volume ratio of isopropanol toethanol in the fuel does not exceed 2:1.

Although conventional processes may produce and/or purify ethanolcompositions, these processes rely on petrochemical feed stocks orfermentation techniques to yield the ethanol compositions.

Therefore, the need exists for an ethanol production process that doesnot rely on petrochemical feed stocks, and does not utilize fermentationtechniques, which can be used to produce denatured fuel ethanolcompositions.

SUMMARY OF THE INVENTION

In one embodiment, the invention is to a denatured fuel ethanolcomposition comprising an ethanol composition and at least 1.96 vol. %of a fuel denaturant. The ethanol composition comprises ethanol andisopropanol. Preferably, the ethanol composition comprises at least 92wt. % ethanol; and from 95 wppm to 1,000 wppm isopropanol. The ethanolcomposition has a high degree of purity and may further comprise lessthan 1 wt. % of one or more organic impurities. These organic impuritiesmay include, for example, acetaldehyde, acetic acid, diethyl acetal,ethyl acetate, n-propanol, butanol, 2-butanol, isobutanol, and mixturesthereof. For example, the ethanol composition may comprise less than 10wppm acetaldehyde; less than 10 wppm of diethyl acetal; and/or less than300 wppm C₄ to C₅ alcohols. In other embodiments, the ethanolcomposition is substantially free of benzene, methanol, and/or C₅alcohols. In other embodiments, the denatured fuel ethanol compositioncomprises less than 1 vol. % water. The denatured fuel ethanolcompositions disclosed herein may be blended with gasolines or dieselfuels and used as motor fuels.

In another embodiment, the invention is to a denatured fuel ethanolcomposition comprising an ethanol composition and at least 1.96 vol. %of a fuel denaturant. The ethanol composition comprises at least 95 wt.% ethanol and at least 95 wppm isopropanol. In another embodiment, theisopropanol is present in an amount less than 1000 wppm. Preferably, theethanol composition further comprises acetaldehyde, and the amount ofacetaldehyde in the ethanol composition is less than the amount ofisopropanol. As one example, the acetaldehyde may be present in anamount less than 10 wppm. In another embodiment, the ethanol compositionfurther comprises n-propanol. Preferably, the weight ratio ofisopropanol to n-propanol ranges from 1:1 to 1:2. The isopropanol may bepresent in an amount of less than 1000 wppm and/or the n-propanol may bepresent in an amount of less than 270 wppm. In other embodiments, thedenatured fuel ethanol composition comprises less than 1 vol. % water.The denatured fuel ethanol composition may be blended with gasoline ordiesel fuel and used as a motor fuel.

In another embodiment, the invention is to a denatured fuel ethanolcomposition comprising an ethanol composition and at least 1.96 vol. %of a fuel denaturant. The ethanol composition comprises at least 92 wt.% ethanol; and at least two other alcohols, which are, optionally,present in an amount less than 1 wt. %. The at least two other alcoholsmay be selected from the group consisting of n-propanol, isopropanol,butanol, 2-butanol, and isobutanol. In another embodiment, one of the atleast two other alcohols is isopropanol and the ethanol compositioncomprises at least 95 wppm isopropanol. The ethanol composition maycomprise isopropanol in an amount less than 1000 wppm. Preferably, theethanol composition is substantially methanol free. In otherembodiments, the denatured fuel ethanol composition comprises less than1 vol. % water. The denatured fuel ethanol composition disclosed hereinmay be blended with gasoline or diesel fuel and used as a motor fuel.

BRIEF DESCRIPTION OF DRAWINGS

The invention is described in detail below with reference to theappended drawings, wherein like numerals designate similar parts.

FIG. 1 is a schematic diagram of a hydrogenation system in accordancewith one embodiment of the present invention.

FIG. 2 is a schematic diagram of the reaction zone in accordance withone embodiment of the present invention.

FIG. 3 is a graph displaying isopropanol contents for severalconventional ethanol compositions.

FIG. 4A is a schematic diagram of a hydrogenation system having a fourthcolumn in accordance with one embodiment of the present invention.

FIG. 4B is a schematic diagram of a hydrogenation system having amolecular sieve unit in accordance with one embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

By “allowable denaturant” is meant natural gasoline, gasolineblendstocks and unleaded gasoline, as permitted by ASTM D4806.

By “denaturant” is meant one or more materials added to ethanol to makeit unsuitable for beverage use under a formula approved by a regulatoryagency to prevent the imposition of beverage alcohol tax.

By “diesel fuel” is meant a mixture of C₉-C₂₄ hydrocarbons that compriseabout 50% to about 95% by volume of aliphatic hydrocarbons, of whichabout 0% to about 50% by volume are cycloparaffins, about 0% to about 5%by volume of olefinic hydrocarbons, and about 5% to about 50% by volumeof aromatic hydrocarbons, and which boil at between about 280° F. (138°C.) and 750° F. (399° C.).

By “natural gasoline” is meant a natural gas liquid having a vaporpressure intermediate between natural gas condensate and liquefiedpetroleum gas and a boiling range within the range of gasoline. Naturalgasoline is liquid at ambient pressure and temperature, may be used todenature ethanol and is an allowable denaturant for denatured fuelethanol.

By “gasoline blendstock” is meant the blendstocks typically available inpetroleum refineries. Such blendstocks include, but are not limited to,alkylate streams, catalytically cracked gasoline streams (e.g., crackednaphtha); aromatic saturated gasoline streams, light straight rungasoline streams, heavy straight run gasoline streams, dehexanizerbottoms streams, dehexanizer overheads streams, hydrocracker topperlight naphtha, reformate, toluene and butane streams. Alkylate streamsare generally obtained by polymerization of isobutane and lower olefincompounds, e.g., butene and propylene, over an acidic catalyst (e.g.,sulfuric acid, hydrofluoric acid, or aluminum chloride). Catalyticallycracked gasoline streams are generally produced from fluid catalyticcrackers (FCC) or thermal catalytic crackers (TCC). Light and heavystraight run gasoline streams are generally obtained by atmosphericdistillation of crude. Reformate streams are generally produced bycatalytic reforming to convert naphthas, typically having low octaneratings, into high-octane liquid products.

By “unleaded gasoline” is meant a volatile mixture of liquidhydrocarbons, generally containing small amounts of additives, suitablefor use as a fuel in spark-ignition, internal combustion engines, thathas not been treated with a lead compound (See ASTM D4814).

The present invention relates to processes for recovering a finishedethanol composition produced by a hydrogenation process for use informing denatured ethanol fuel compositions and to denatured ethanolfuel compositions. The hydrogenation process comprises hydrogenatingacetic acid in the presence of a catalyst. The hydrogenation processproduces a crude ethanol product that is different from the crudeethanol composition produced by other ethanol production processes. Forexample, fermentation processes produce crude ethanol compositionshaving low ethanol content. Crude ethanol compositions produced frompetrochemical feed stocks produces crude ethanol compositions comprisingother alcohols, especially methanol, n-propanol and higher alcohols. Thecrude ethanol product produced hydrogenation of acetic acid preferableis separated to remove impurities and recover a finished ethanolcomposition.

The inventive ethanol composition, in one embodiment, comprises a majorportion of ethanol and a minor portion of isopropanol. The ethanolcomposition is primarily ethanol and contains from 92 wt. % to 96 wt. %ethanol, e.g., from 93 wt. % to 96 wt. %, or from 95 wt. % to 96 wt. %.Preferably, the ethanol composition comprises at least 92 wt. % ethanol,e.g., at least 93 wt. %, or at least 95 wt. %. Higher amounts ofethanol, for example anhydrous ethanol, may be possible by furtherremoving the water of the ethanol composition. The isopropanol may bepresent in amounts ranging from 95 wppm to 1,000 wppm, e.g., from 110wppm to 800 wppm, or from 110 wppm to 400 wppm. In terms of lowerlimits, in one embodiment, the ethanol composition comprises at least 95wppm isopropanol, e.g., at least 110 wppm or at least 150 wppm. In termsof upper limits, in one embodiment, the ethanol composition comprisesless than 1,000 wppm isopropanol, e.g., less than 800 wppm or less than400 wppm. In contrast, FIG. 3 displays isopropanol levels of 176conventional ethanol compositions. These ethanol compositions werederived from various conventional sources and techniques such assugarcane fermentation, molasses fermentation, and Fischer-Tropschsynthesis. As shown in FIG. 3, each of these conventional ethanolcompositions has a very low isopropanol concentration, and none compriseisopropanol in an amount greater than 94 wppm.

In one embodiment, the ethanol composition further comprises water, forexample, in an amount less than 8 wt. % water, less than 5 wt. % or lessthan 2 wt. %. In another embodiment, the weight ratio of isopropanol towater in the ethanol composition ranges from 1:80 to 1:800, e.g. from1:100 to 1:500. In one embodiment, the ethanol composition comprisesessentially no other detectable compounds, such as methanol, benzene,and/or higher alcohols, e.g., C₄₊ alcohols. In some embodiments, theethanol composition may comprise minor amounts of other impurities, suchas those described below in Table 7.

In another embodiment, the invention is to an ethanol compositioncomprising ethanol and at least two other alcohols. The at least twoother alcohols may be selected from the group consisting of n-propanol,isopropanol, butanol, 2-butanol, and isobutanol. Preferably, one of theat least two other alcohols is isopropanol. In these embodiments, theisopropanol is present in an amount of at least 95 wppm isopropanol,e.g., at least 110 wppm or at least 150 wppm. In preferred embodiments,when the weight percentages of the at least two other alcohols are addedtogether, the at least two other alcohols, collectively, are present inan amount of less than 1 wt. %.

Without being bound by theory, it is believed that isopropanol is formedduring the hydrogenation of acetic acid. For example, the isopropanolmay be formed via the hydrogenation of acetone. The acetone may begenerated via an acetic acid ketonization reaction. The n-propanol, ifpresent in the ethanol composition, is believed to be formed fromimpurities in the acetic acid feed. The ethanol compositions of thepresent invention preferably comprise n-propanol in an amount less than0.5 wt. % n-propanol, e.g., less than 0.1 wt. % or less than 0.05 wt. %.Optionally, ethanol compositions of the present invention may preferablyhave less n-propanol than isopropanol. The ethanol compositions formedby the inventive processes comprise a higher amount of in situ-formedisopropanol than conventional ethanol compositions. Preferably, in theinventive ethanol compositions, the amount of n-propanol is less thanthe amount of isopropanol, e.g., less than 10% the amount of isopropanolor less than 50% the amount of isopropanol. Further, in one embodiment,the weight ratio of isopropanol to n-propanol in the inventive ethanolcomposition may range from 0.1:1 to 10:1, e.g., from 0.5:1 to 10:1, from1:1 to 5:1, or from 1:1 to 2:1. In terms of limits, the weight ratio ofisopropanol to n-propanol may be at least 0.5:1, e.g., at least 1:1, atleast 1.5:1, at least 2:1, at least 5:1 or at least 10:1. Inconventional ethanol production processes, isopropanol is typically notpresent in the amounts discussed above. Thus, the weight ratio ofisopropanol or n-propanol favors more n-propanol, e.g., greater than10:1.

In one embodiment of the present invention, isopropanol preferably isnot added to the finished ethanol composition after the separation andrecovery of ethanol. The isopropanol formed during the hydrogenation ofacetic acid may be carried with the ethanol through the separationprocess.

In addition, conventional hydrogenation reactions often form higheramounts of acetaldehyde, as compared to isopropanol. The inventiveethanol compositions comprise low amounts of acetaldehyde, as well asother acetal compounds. Preferably, in the inventive ethanolcompositions, the amount of acetaldehyde is less than the amount ofisopropanol. For example, the amount of acetaldehyde may be less than50% of the amount of isopropanol, e.g., less than 10% of the amount ofisopropanol or less than 5% of the amount of isopropanol. Further theweight ratio of isopropanol to acetaldehyde in the inventive ethanolcomposition may range from 1:100 to 1:1000, e.g., from 1:100 to 1:500.

In one embodiment, the ethanol composition of the present inventioncomprises minor amounts of organic impurities. These organic impuritiesmay include acetaldehyde, acetic acid, diethyl acetal, ethyl acetate,n-propanol, methanol, butanol, 2-butanol, isobutanol, isoamyl alcohol,amyl alcohol, benzene and/or mixtures thereof. Beneficially, in oneembodiment, the ethanol composition comprises less than 1 wt. % organicimpurities, e.g., less than 0.75 wt. % or less than 0.5 wt. %. Dependingon the amount of these organic impurities, the impurities may havedetrimental effects on the ethanol composition. For example, otheralcohols in the crude ethanol composition may esterify with the aceticacid to form other esters. Also, it has been found that isobutanol,iso-amyl alcohol, and 2-methyl-1-butanol (“active amyl alcohol”)contribute to residual odor in ethanol and ethyl acetate compositions.

In preferred embodiments, the ethanol composition is substantiallymethanol-free and may comprise less than 10 wppm methanol, e.g., lessthan 1 wppm. In addition, in preferred embodiments, the ethanolcomposition is substantially free of C₅ alcohols and may comprises lessthan 10 wppm of C₅ alcohols, e.g., less than 1 wppm.

Benzene, dioxanes, and cyanides are known to present toxicity issues inethanol compositions. Typically, cyanides result from fermentationmethods that utilize cassava as a feed stock. The inventive ethanolcompositions comprise low amounts of these components. Preferably, theethanol composition contains no detectable amount of benzene, dioxanes,and cyanides.

Hydrogenation Process

Turning to the production of the crude ethanol composition, generally,the hydrogenation of acetic acid forms ethanol and water as shown by thefollowing reaction:

In addition to water and ethanol, other compounds may be formed duringthe hydrogenation of the acetic, as discussed below in Table 1.

Suitable hydrogenation catalysts include catalysts comprising a firstmetal and optionally one or more of a second metal, a third metal oradditional metals, optionally on a catalyst support. The first andoptional second and third metals may be selected from Group IB, IIB,IIIB, IVB, VB, VIB, VIIB, VIII transitional metals, a lanthanide metal,an actinide metal or a metal selected from any of Groups IIIA, IVA, VA,and VIA. Preferred metal combinations for some exemplary catalystcompositions include platinum/tin, platinum/ruthenium, platinum/rhenium,palladium/ruthenium, palladium/rhenium, cobalt/palladium,cobalt/platinum, cobalt/chromium, cobalt/ruthenium, silver/palladium,copper/palladium, nickel/palladium, gold/palladium, ruthenium/rhenium,and ruthenium/iron. Exemplary catalysts are further described in U.S.Pat. No. 7,608,744 and U.S. Publication No. 2010/0029995, the entiretiesof which are incorporated herein by reference. Additional catalysts aredescribed in U.S. application Ser. No. 12/698,968, entitled “Catalystsfor Making Ethanol from Acetic Acid,” filed on Feb. 2, 2010, theentirety of which is incorporated herein by reference.

In one exemplary embodiment, the catalyst comprises a first metalselected from the group consisting of copper, iron, cobalt, nickel,ruthenium, rhodium, palladium, osmium, iridium, platinum, titanium,zinc, chromium, rhenium, molybdenum, and tungsten. Preferably, the firstmetal is selected from the group consisting of platinum, palladium,cobalt, nickel, and ruthenium. More preferably, the first metal isselected from platinum and palladium. When the first metal comprisesplatinum, it is preferred that the catalyst comprises platinum in anamount less than 5 wt. %, e.g., less than 3 wt. % or less than 1 wt. %,due to the high demand for platinum.

As indicated above, the catalyst optionally further comprises a secondmetal, which typically would function as a promoter. If present, thesecond metal preferably is selected from the group consisting of copper,molybdenum, tin, chromium, iron, cobalt, vanadium, tungsten, palladium,platinum, lanthanum, cerium, manganese, ruthenium, rhenium, gold, andnickel. More preferably, the second metal is selected from the groupconsisting of copper, tin, cobalt, rhenium, and nickel. More preferably,the second metal is selected from tin and rhenium.

If the catalyst includes two or more metals, e.g., a first metal and asecond metal, the first metal optionally is present in the catalyst inan amount from 0.1 to 10 wt. %, e.g., from 0.1 to 5 wt. %, or from 0.1to 3 wt. %. The second metal preferably is present in an amount from 0.1and 20 wt. %, e.g., from 0.1 to 10 wt. %, or from 0.1 to 5 wt. %. Forcatalysts comprising two or more metals, the two or more metals may bealloyed with one another or may comprise a non-alloyed metal solution ormixture.

The preferred metal ratios may vary depending on the metals used in thecatalyst. In some exemplary embodiments, the mole ratio of the firstmetal to the second metal is from 10:1 to 1:10, e.g., from 4:1 to 1:4,from 2:1 to 1:2, from 1.5:1 to 1:1.5 or from 1.1:1 to 1:1.1.

The catalyst may also comprise a third metal selected from any of themetals listed above in connection with the first or second metal, solong as the third metal is different from the first and second metals.In preferred aspects, the third metal is selected from the groupconsisting of cobalt, palladium, ruthenium, copper, zinc, platinum, tin,and rhenium. More preferably, the third metal is selected from cobalt,palladium, and ruthenium. When present, the total weight of the thirdmetal preferably is from 0.05 and 4 wt. %, e.g., from 0.1 to 3 wt. %, orfrom 0.1 to 2 wt. %.

In addition to one or more metals, the exemplary catalysts furthercomprise a support or a modified support, meaning a support thatincludes a support material and a support modifier, which adjusts theacidity of the support material. The total weight of the support ormodified support, based on the total weight of the catalyst, preferablyis from 75 wt. % to 99.9 wt. %, e.g., from 78 wt. % to 97 wt. %, or from80 wt. % to 95 wt. %. In preferred embodiments that use a modifiedsupport, the support modifier is present in an amount from 0.1 wt. % to50 wt. %, e.g., from 0.2 wt. % to 25 wt. %, from 0.5 wt. % to 15 wt. %,or from 1 wt. % to 8 wt. %, based on the total weight of the catalyst.

Suitable support materials may include, for example, stable metaloxide-based supports or ceramic-based supports. Preferred supportsinclude silicaceous supports, such as silica, silica/alumina, and aGroup IIA silicate such as calcium metasilicate, pyrogenic silica, highpurity silica, and mixtures thereof. Other supports may include, but arenot limited to, iron oxide, alumina, titania, zirconia, magnesium oxide,carbon, graphite, high surface area graphitized carbon, activatedcarbons, and mixtures thereof.

In the production of ethanol, the catalyst support may be modified witha support modifier. Preferably, the support modifier is a basic modifierthat has a low volatility or no volatility. Such basic modifiers, forexample, may be selected from the group consisting of: (i) alkalineearth oxides, (ii) alkali metal oxides, (iii) alkaline earth metalmetasilicates, (iv) alkali metal metasilicates, (v) Group IIB metaloxides, (vi) Group IIB metal metasilicates, (vii) Group IIIB metaloxides, (viii) Group IIIB metal metasilicates, and mixtures thereof. Inaddition to oxides and metasilicates, other types of modifiers includingnitrates, nitrites, acetates, and lactates may be used. Preferably, thesupport modifier is selected from the group consisting of oxides andmetasilicates of any of sodium, potassium, magnesium, calcium, scandium,yttrium, and zinc, as well as mixtures of any of the foregoing.Preferably, the support modifier is a calcium silicate, and morepreferably calcium metasilicate (CaSiO₃). If the support modifiercomprises calcium metasilicate, it is preferred that at least a portionof the calcium metasilicate is in crystalline form.

A preferred silica support material is SS61138 High Surface Area (HSA)Silica Catalyst Carrier from Saint-Gobain NorPro. The Saint-GobainNorPro SS61138 silica contains approximately 95 wt. % high surface areasilica; a surface area of about 250 m²/g; a median pore diameter ofabout 12 nm; an average pore volume of about 1.0 cm³/g as measured bymercury intrusion porosimetry and a packing density of about 0.352 g/cm³(22 lb/ft³).

A preferred silica/alumina support material is KA-160 (Sud Chemie)silica spheres having a nominal diameter of about 5 mm, a density ofabout 0.562 g/ml, in absorptivity of about 0.583 g H₂O/g support, asurface area of about 160 to 175 m²/g, and a pore volume of about 0.68ml/g.

As will be appreciated by those of ordinary skill in the art, supportmaterials are selected such that the catalyst system is suitably active,selective and robust under the process conditions employed for theformation of ethanol.

The metals of the catalysts may be dispersed throughout the support,coated on the outer surface of the support (egg shell) or decorated onthe surface of the support.

The catalyst compositions suitable for use with the present inventionpreferably are formed through metal impregnation of the modifiedsupport, although other processes such as chemical vapor deposition mayalso be employed. Such impregnation techniques are described in U.S.Pat. No. 7,608,744, U.S. Publication No. 2010/0029995, and U.S.application Ser. No. 12/698,968, referred to above, the entireties ofwhich are incorporated herein by reference.

Some embodiments of the process of hydrogenating acetic acid to formethanol according to one embodiment of the invention may include avariety of configurations using a fixed bed reactor or a fluidized bedreactor, as one of skill in the art will readily appreciate. In manyembodiments of the present invention, an “adiabatic” reactor can beused; that is, there is little or no need for internal plumbing throughthe reaction zone to add or remove heat. In other embodiments, radialflow reactor or reactors may be employed, or a series of reactors may beemployed with or with out heat exchange, quenching, or introduction ofadditional feed material. Alternatively, a shell and tube reactorprovided with a heat transfer medium may be used. In many cases, thereaction zone may be housed in a single vessel or in a series of vesselswith heat exchangers therebetween.

In preferred embodiments, the catalyst is employed in a fixed bedreactor, e.g., in the shape of a pipe or tube, where the reactants,typically in the vapor form, are passed over or through the catalyst.Other reactors, such as fluid or ebullient bed reactors, can beemployed. In some instances, the hydrogenation catalysts may be used inconjunction with an inert material to regulate the pressure drop of thereactant stream through the catalyst bed and the contact time of thereactant compounds with the catalyst particles.

The hydrogenation reaction may be carried out in either the liquid phaseor vapor phase. Preferably, the reaction is carried out in the vaporphase under the following conditions. The reaction temperature may rangefrom 125° C. to 350° C., e.g., from 200° C. to 325° C., from 225° C. to300° C., or from 250° C. to 300° C. The pressure may range from 10 KPato 3000 KPa (about 1.5 to 435 psi), e.g., from 50 KPa to 2300 KPa, orfrom 100 KPa to 1500 KPa. The reactants may be fed to the reactor at agas hourly space velocity (GHSV) of greater than 500 hr⁻¹, e.g., greaterthan 1000 hr⁻¹, greater than 2500 hr⁻¹ or even greater than 5000 hr⁻¹.In terms of ranges the GHSV may range from 50 hr⁻¹to 50,000 hr⁻¹, e.g.,from 500 hr⁻¹ to 30,000 hr⁻¹, from 1000 hr⁻¹ to 10,000 hr⁻¹, or from1000 hr⁻¹ to 6500 hr⁻¹.

The hydrogenation optionally is carried out at a pressure justsufficient to overcome the pressure drop across the catalytic bed at theGHSV selected, although there is no bar to the use of higher pressures,it being understood that considerable pressure drop through the reactorbed may be experienced at high space velocities, e.g., 5000 hr⁻¹ or6,500 hr⁻¹.

Although the reaction consumes two moles of hydrogen per mole of aceticacid to produce one mole of ethanol, the actual molar ratio of hydrogento acetic acid in the feed stream may vary from about 100:1 to 1:100,e.g., from 50:1 to 1:50, from 20:1 to 1:2, or from 12:1 to 1:1. Mostpreferably, the molar ratio of hydrogen to acetic acid is greater than2:1, e.g., greater than 4:1 or greater than 8:1.

Contact or residence time can also vary widely, depending upon suchvariables as amount of acetic acid, catalyst, reactor, temperature andpressure. Typical contact times range from a fraction of a second tomore than several hours when a catalyst system other than a fixed bed isused, with preferred contact times, at least for vapor phase reactions,of from 0.1 to 100 seconds, e.g., from 0.3 to 80 seconds or from 0.4 to30 seconds.

The raw materials, acetic acid and hydrogen, used in connection with theprocess of this invention may be derived from any suitable sourceincluding natural gas, petroleum, coal, biomass, and so forth. Asexamples, acetic acid may be produced via methanol carbonylation,acetaldehyde oxidation, ethylene oxidation, oxidative fermentation, andanaerobic fermentation. As petroleum and natural gas prices fluctuate,becoming either more or less expensive methods for producing acetic acidand intermediates such as methanol and carbon monoxide from alternatecarbon sources have drawn increasing interest. In particular, whenpetroleum is relatively expensive compared to natural gas, it may becomeadvantageous to produce acetic acid from synthesis gas (“syn gas”) thatis derived from any available carbon source. U.S. Pat. No. 6,232,352,the disclosure of which is incorporated herein by reference, forexample, teaches a method of retrofitting a methanol plant for themanufacture of acetic acid. By retrofitting a methanol plant, the largecapital costs associated with CO generation for a new acetic acid plantare significantly reduced or largely eliminated. All or part of the syngas is diverted from the methanol synthesis loop and supplied to aseparator unit to recover CO and hydrogen, which are then used toproduce acetic acid. In addition to acetic acid, such a process can alsobe used to make hydrogen which may be utilized in connection with thisinvention.

Methanol carbonylation processes suitable for production of acetic acidare described in U.S. Pat. Nos. 7,208,624, 7,115,772, 7,005,541,6,657,078, 6,627,770, 6,143,930, 5,599,976, 5,144,068, 5,026,908,5,001,259, and 4,994,608, the disclosure of which is incorporated hereinby reference. Optionally, the production of ethanol may be integratedwith such methanol carbonylation processes.

U.S. Pat. No. RE 35,377 also incorporated herein by reference, providesa method for the production of methanol by conversion of carbonaceousmaterials such as oil, coal, natural gas and biomass materials. Theprocess includes hydrogasification of solid and/or liquid carbonaceousmaterials to obtain a process gas which is steam pyrolized withadditional natural gas to form synthesis gas. The syn gas is convertedto methanol which may be carbonylated to acetic acid. The methodlikewise produces hydrogen which may be used in connection with thisinvention as noted above. U.S. Pat. No. 5,821,111, which discloses aprocess for converting waste biomass through gasification into synthesisgas as well as U.S. Pat. No. 6,685,754, the disclosures of which areincorporated herein by reference.

In one optional embodiment, the acetic acid fed to the hydrogenationreaction may also comprise other carboxylic acids and anhydrides, aswell as acetaldehyde and acetone. Preferably, a suitable acetic acidfeed stream comprises one or more of the compounds selected from thegroup consisting of acetic acid, acetic anhydride, acetaldehyde, andmixtures thereof. These other compounds may also be hydrogenated in theprocesses of the present invention. In some embodiments, the present ofcarboxylic acids, such as propanoic acid or its anhydride, may bebeneficial in producing propanol.

Alternatively, acetic acid in vapor form may be taken directly as crudeproduct from the flash vessel of a methanol carbonylation unit of theclass described in U.S. Pat. No. 6,657,078, the entirety of which isincorporated herein by reference. The crude vapor product, for example,may be fed directly to the ethanol synthesis reaction zones of thepresent invention without the need for condensing the acetic acid andlight ends or removing water, saving overall processing costs.

The acetic acid may be vaporized at the reaction temperature, followingwhich the vaporized acetic acid can be fed along with hydrogen in anundiluted state or diluted with a relatively inert carrier gas, such asnitrogen, argon, helium, carbon dioxide and the like. For reactions runin the vapor phase, the temperature should be controlled in the systemsuch that it does not fall below the dew point of acetic acid. In oneembodiment the acetic acid may be vaporized at the boiling point ofacetic acid at the particular pressure, and then the vaporized aceticacid may be further heated to the reactor inlet temperature. In anotherembodiment, the acetic acid is transferred to the vapor state by passinghydrogen, recycle gas, another suitable gas, or mixtures thereof throughthe acetic acid at a temperature below the boiling point of acetic acid,thereby humidifying the carrier gas with acetic acid vapors, followed byheating the mixed vapors up to the reactor inlet temperature.Preferably, the acetic acid is transferred to the vapor by passinghydrogen and/or recycle gas through the acetic acid at a temperature ator below 125° C., followed by heating of the combined gaseous stream tothe reactor inlet temperature.

In particular, the hydrogenation of acetic acid may achieve favorableconversion of acetic acid and favorable selectivity and productivity toethanol. For purposes of the present invention, the term “conversion”refers to the amount of acetic acid in the feed that is converted to acompound other than acetic acid. Conversion is expressed as a molepercentage based on acetic acid in the feed. The conversion may be atleast 10%, e.g., at least 20%, at least 40%, at least 50%, at least 60%,at least 70% or at least 80%. Although catalysts that have highconversions are desirable, such as at least 80% or at least 90%, in someembodiments a low conversion may be acceptable at high selectivity forethanol. It is, of course, well understood that in many cases, it ispossible to compensate for conversion by appropriate recycle streams oruse of larger reactors, but it is more difficult to compensate for poorselectivity.

Selectivity is expressed as a mole percent based on converted aceticacid. It should be understood that each compound converted from aceticacid has an independent selectivity and that selectivity is independentfrom conversion. For example, if 50 mole % of the converted acetic acidis converted to ethanol, we refer to the ethanol selectivity as 50%.Preferably, the catalyst selectivity to ethoxylates is at least 60%,e.g., at least 70%, or at least 80%. As used herein, the term“ethoxylates” refers specifically to the compounds ethanol,acetaldehyde, and ethyl acetate. Preferably, the selectivity to ethanolis at least 80%, e.g., at least 85% or at least 88%. Preferredembodiments of the hydrogenation process also have low selectivity toundesirable products, such as methane, ethane, and carbon dioxide. Theselectivity to these undesirable products preferably is less than 4%,e.g., less than 2% or less than 1%. More preferably, these undesirableproducts are not detectable. Formation of alkanes may be low, andideally less than 2%, less than 1%, or less than 0.5% of the acetic acidpassed over the catalyst is converted to alkanes, which have littlevalue other than as fuel.

The term “productivity,” as used herein, refers to the grams of aspecified product, e.g., ethanol, formed during the hydrogenation basedon the kilograms of catalyst used per hour. A productivity of at least200 grams of ethanol per kilogram catalyst per hour, e.g., at least 400grams of ethanol per kilogram catalyst per hour or at least 600 grams ofethanol per kilogram catalyst per hour, is preferred. In terms ofranges, the productivity preferably is from 200 to 3,000 grams ofethanol per kilogram catalyst per hour, e.g., from 400 to 2,500 perkilogram catalyst per hour or from 600 to 2,000 per kilogram catalystper hour.

In various embodiments, the crude ethanol product produced by thehydrogenation process, before any subsequent processing, such aspurification and separation, will typically comprise unreacted aceticacid, ethanol and water. As used herein, the term “crude ethanolproduct” refers to any composition comprising from 5 to 70 wt. % ethanoland from 5 to 35 wt. % water. In some exemplary embodiments, the crudeethanol product comprises ethanol in an amount from 5 wt. % to 70 wt. %,e.g., from 10 wt. % to 60 wt. %, or from 15 wt. % to 50 wt. %, based onthe total weight of the crude ethanol product. Preferably, the crudeethanol product contains at least 10 wt. % ethanol, at least 15 wt. %ethanol or at least 20 wt. % ethanol.

The crude ethanol product typically will further comprise unreactedacetic acid, depending on conversion, for example, in an amount of lessthan 90 wt. %, e.g., less than 80 wt. % or less than 70 wt. %. In termsof ranges, the unreacted acetic acid is preferably from 0 to 90 wt. %,e.g., from 5 to 80 wt. %, from 15 to 70 wt. %, from 20 to 70 wt. % orfrom 25 to 65 wt. %. As water is formed in the reaction process, waterwill generally be present in the crude ethanol product, for example, inamounts ranging from 5 to 35 wt. %, e.g., from 10 to 30 wt. % or from 10to 26 wt. %. Ethyl acetate may also be produced during the hydrogenationof acetic acid or through side reactions and may be present, forexample, in amounts ranging from 0 to 20 wt. %, e.g., from 0 to 15 wt.%, from 1 to 12 wt. % or from 3 to 10 wt. %. Acetaldehyde may also beproduced through side reactions and may be present, for example, inamounts ranging from 0 to 10 wt. %, e.g., from 0 to 3 wt. %, from 0.1 to3 wt. % or from 0.2 to 2 wt. %.

Other components, such as, for example, esters, ethers, aldehydes,ketones, alkanes, and carbon dioxide, if detectable, collectively may bepresent in amounts less than 10 wt. %, e.g., less than 6 wt. % or lessthan 4 wt. %. In terms of ranges, other components may be present in anamount from 0.1 to 10 wt. %, e.g., from 0.1 to 6 wt. %, or from 0.1 to 4wt. %. Exemplary embodiments of crude ethanol compositional ranges areprovided in Table 1.

TABLE 1 CRUDE ETHANOL PRODUCT COMPOSITIONS Conc. Conc. Conc. Conc.Component (wt. %) (wt. %) (wt. %) (wt. %) Ethanol 5 to 70 10 to 60  15to 50 25 to 50 Acetic Acid 0 to 90 5 to 80 15 to 70 20 to 70 Water 5 to35 5 to 30 10 to 30 10 to 26 Ethyl Acetate 0 to 20 0 to 15  1 to 12  3to 10 Acetaldehyde 0 to 10 0 to 3  0.1 to 3  0.2 to 2  Others 0.1 to 10 0.1 to 6   0.1 to 4  —Purification

FIG. 1 shows a hydrogenation system 100 suitable for the hydrogenationof acetic acid and separating ethanol from the crude reaction mixtureaccording to one embodiment of the invention. System 100 comprisesreaction zone 101 and distillation zone 102. Reaction zone 101 comprisesreactor 103, hydrogen feed line 104 and acetic acid feed line 105.Distillation zone 102 comprises flasher 106, first column 107, secondcolumn 108, third column 109, and fourth column 123. Hydrogen and aceticacid are fed to a vaporizer 110 via lines 104 and 105, respectively, tocreate a vapor feed stream in line 111 that is directed to reactor 103.In one embodiment, lines 104 and 105 may be combined and jointly fed tothe vaporizer 110, e.g., in one stream containing both hydrogen andacetic acid. The temperature of the vapor feed stream in line 111 ispreferably from 100° C. to 350° C., e.g., from 120° C. to 310° C. orfrom 150° C. to 300° C. Any feed that is not vaporized is removed fromvaporizer 110, as shown in FIG. 1, and may be recycled thereto. Inaddition, although FIG. 1 shows line 111 being directed to the top ofreactor 103, line 111 may be directed to the side, upper portion, orbottom of reactor 103. Further modifications and additional componentsto reaction zone 101 are described below in FIG. 2.

Reactor 103 contains the catalyst that is used in the hydrogenation ofthe carboxylic acid, preferably acetic acid. In one embodiment, one ormore guard beds (not shown) may be used to protect the catalyst frompoisons or undesirable impurities contained in the feed orreturn/recycle streams. Such guard beds may be employed in the vapor orliquid streams. Suitable guard bed materials are known in the art andinclude, for example, carbon, silica, alumina, ceramic, or resins. Inone aspect, the guard bed media is functionalized to trap particularspecies such as sulfur or halogens. During the hydrogenation process, acrude ethanol product is withdrawn, preferably continuously, fromreactor 103 via line 112. The crude ethanol product may be condensed andfed to flasher 106, which, in turn, provides a vapor stream and a liquidstream. The flasher 106 in one embodiment preferably operates at atemperature of from 50° C. to 500° C., e.g., from 70° C. to 400° C. orfrom 100° C. to 350° C. In one embodiment, the pressure of flasher 106preferably is from 50 KPa to 2000 KPa, e.g., from 75 KPa to 1500 KPa orfrom 100 to 1000 KPa. In one preferred embodiment the temperature andpressure of the flasher is similar to the temperature and pressure ofthe reactor 103.

The vapor stream exiting the flasher 106 may comprise hydrogen andhydrocarbons, which may be purged and/or returned to reaction zone 101via line 113. As shown in FIG. 1, the returned portion of the vaporstream passes through compressor 114 and is combined with the hydrogenfeed and co-fed to vaporizer 110.

The liquid from flasher 106 is withdrawn and pumped as a feedcomposition via line 115 to the side of first column 107, also referredto as the acid separation column. The contents of line 115 typicallywill be substantially similar to the product obtained directly from thereactor, and may, in fact, also be characterized as a crude ethanolproduct. However, the feed composition in line 115 preferably hassubstantially no hydrogen, carbon dioxide, methane or ethane, which areremoved by flasher 106. Exemplary components of liquid in line 115 areprovided in Table 2. It should be understood that liquid line 115 maycontain other components, not listed, such as components in the feed.

TABLE 2 FEED COMPOSITION Conc. (wt. %) Conc. (wt. %) Conc. (wt. %)Ethanol 5 to 70    10 to 60 15 to 50 Acetic Acid <90    5 to 80 15 to 70Water 5 to 35    5 to 30 10 to 30 Ethyl Acetate <20  0.001 to 15  1 to12 Acetaldehyde <10 0.001 to 3 0.1 to 3  Acetal <5 0.001 to 2 0.005 to1    Acetone <5  0.0005 to 0.05 0.001 to 0.03  Other Esters <5 <0.005<0.001 Other Ethers <5 <0.005 <0.001 Other Alcohols <5 <0.005 <0.001

The amounts indicated as less than (<) in the tables throughout thepresent application are preferably not present and if present may bepresent in trace amounts or in amounts greater than 0.0001 wt. %.

The “other esters” in Table 2 may include, but are not limited to, ethylpropionate, methyl acetate, isopropyl acetate, n-propyl acetate, n-butylacetate or mixtures thereof. The “other ethers” in Table 2 may include,but are not limited to, diethyl ether, methyl ethyl ether, isobutylethyl ether or mixtures thereof. The “other alcohols” in Table 2 mayinclude, but are not limited to, methanol, isopropanol, n-propanol,n-butanol or mixtures thereof. In one embodiment, the feed composition,e.g., line 115, may comprise propanol, e.g., isopropanol and/orn-propanol, in an amount from 0.001 to 0.1 wt. %, from 0.001 to 0.05 wt.% or from 0.001 to 0.03 wt. %. In should be understood that these othercomponents may be carried through in any of the distillate or residuestreams described herein and will not be further described herein,unless indicated otherwise.

When the content of acetic acid in line 115 is less than 5 wt. %, theacid separation column 107 may be skipped and line 115 may be introduceddirectly to second column 108, also referred to herein as a light endscolumn.

In the embodiment shown in FIG. 1, line 115 is introduced in the lowerpart of first column 107, e.g., lower half or lower third. In firstcolumn 107, unreacted acetic acid, a portion of the water, and otherheavy components, if present, are removed from the composition in line115 and are withdrawn, preferably continuously, as residue. Some or allof the residue may be returned and/or recycled back to reaction zone 101via line 116. First column 107 also forms an overhead distillate, whichis withdrawn in line 117, and which may be condensed and refluxed, forexample, at a ratio of from 10:1 to 1:10, e.g., from 3:1 to 1:3 or from1:2 to 2:1.

Any of columns 107, 108, 109, or 123 may comprise any distillationcolumn capable of separation and/or purification. The columns preferablycomprise tray columns having from 1 to 150 trays, e.g., from 10 to 100trays, from 20 to 95 trays or from 30 to 75 trays. The trays may besieve trays, fixed valve trays, movable valve trays, or any othersuitable design known in the art. In other embodiments, a packed columnmay be used. For packed columns, structured packing or random packingmay be employed. The trays or packing may be arranged in one continuouscolumn or they may be arranged in two or more columns such that thevapor from the first section enters the second section while the liquidfrom the second section enters the first section, etc.

The associated condensers and liquid separation vessels that may beemployed with each of the distillation columns may be of anyconventional design and are simplified in FIG. 1. As shown in FIG. 1,heat may be supplied to the base of each column or to a circulatingbottom stream through a heat exchanger or reboiler. Other types ofreboilers, such as internal reboilers, may also be used in someembodiments. The heat that is provided to reboilers may be derived fromany heat generated during the process that is integrated with thereboilers or from an external source such as another heat generatingchemical process or a boiler. Although one reactor and one flasher areshown in FIG. 1, additional reactors, flashers, condensers, heatingelements, and other components may be used in embodiments of the presentinvention. As will be recognized by those skilled in the art, variouscondensers, pumps, compressors, reboilers, drums, valves, connectors,separation vessels, etc., normally employed in carrying out chemicalprocesses may also be combined and employed in the processes of thepresent invention.

The temperatures and pressures employed in any of the columns may vary.As a practical matter, pressures from 10 KPa to 3000 KPa will generallybe employed in these zones although in some embodiments subatmosphericpressures may be employed as well as superatmospheric pressures.Temperatures within the various zones will normally range between theboiling points of the composition removed as the distillate and thecomposition removed as the residue. It will be recognized by thoseskilled in the art that the temperature at a given location in anoperating distillation column is dependent on the composition of thematerial at that location and the pressure of column. In addition, feedrates may vary depending on the size of the production process and, ifdescribed, may be generically referred to in terms of feed weightratios.

When column 107 is operated under standard atmospheric pressure, thetemperature of the residue exiting in line 116 from column 107preferably is from 95° C. to 120° C., e.g., from 105° C. to 117° C. orfrom 110° C. to 115° C. The temperature of the distillate exiting inline 117 from column 107 preferably is from 70° C. to 110° C., e.g.,from 75° C. to 95° C. or from 80° to 90° C. In other embodiments, thepressure of first column 107 may range from 0.1 KPa to 510 KPa, e.g.,from 1 KPa to 475 KPa or from 1 KPa to 375 KPa. Exemplary components ofthe distillate and residue compositions for first column 107 areprovided in Table 3 below. It should also be understood that thedistillate and residue may also contain other components, not listed,such as components in the feed. For convenience, the distillate andresidue of the first column may also be referred to as the “firstdistillate” or “first residue.” The distillates or residues of the othercolumns may also be referred to with similar numeric modifiers (second,third, etc.) in order to distinguish them from one another, but suchmodifiers should not be construed as requiring any particular separationorder.

TABLE 3 FIRST COLUMN Conc. (wt. %) Conc. (wt. %) Conc. (wt. %)Distillate Ethanol 20 to 75 30 to 70 40 to 65 Water 10 to 40 15 to 35 20to 35 Acetic Acid <2 0.001 to 0.5  0.01 to 0.2  Ethyl Acetate <60 5.0 to40  10 to 30 Acetaldehyde <10 0.001 to 5    0.01 to 4   Acetal <0.1 <0.1<0.05 Acetone <0.05 0.001 to 0.03   0.01 to 0.025 Residue Acetic Acid 60 to 100 70 to 95 85 to 92 Water <30  1 to 20  1 to 15 Ethanol <1 <0.9<0.07

As shown in Table 3, without being bound by theory, it has surprisinglyand unexpectedly been discovered that when any amount of acetal isdetected in the feed that is introduced to the acid separation column(first column 107), the acetal appears to decompose in the column suchthat less or even no detectable amounts are present in the distillateand/or residue.

Depending on the reaction conditions, the crude ethanol product exitingreactor 103 in line 112 may comprise ethanol, acetic acid (unconverted),ethyl acetate, and water. After exiting reactor 103, a non-catalyzedequilibrium reaction may occur between the components contained in thecrude ethanol product until it is added to flasher 106 and/or firstcolumn 107. This equilibrium reaction tends to drive the crude ethanolproduct to an equilibrium between ethanol/acetic acid and ethylacetate/water, as shown below.EtOH+HOAc⇄EtOAc+H₂O

In the event the crude ethanol product is temporarily stored, e.g., in aholding tank, prior to being directed to distillation zone 102, extendedresidence times may be encountered. Generally, the longer the residencetime between reaction zone 101 and distillation zone 102, the greaterthe formation of ethyl acetate. For example, when the residence timebetween reaction zone 101 and distillation zone 102 is greater than 5days, significantly more ethyl acetate may form at the expense ofethanol. Thus, shorter residence times between reaction zone 101 anddistillation zone 102 are generally preferred in order to maximize theamount of ethanol formed. In one embodiment, a holding tank (not shown),is included between the reaction zone 101 and distillation zone 102 fortemporarily storing the liquid component from line 115 for up to 5 days,e.g., up to 1 day, or up to 1 hour. In a preferred embodiment no tank isincluded and the condensed liquids are fed directly to the firstdistillation column 107. In addition, the rate at which thenon-catalyzed reaction occurs may increase as the temperature of thecrude ethanol product, e.g., in line 115, increases. These reactionrates may be particularly problematic at temperatures exceeding 30° C.,e.g., exceeding 40° C. or exceeding 50° C. Thus, in one embodiment, thetemperature of liquid components in line 115 or in the optional holdingtank is maintained at a temperature less than 40° C., e.g., less than30° C. or less than 20° C. One or more cooling devices may be used toreduce the temperature of the liquid in line 115.

As discussed above, a holding tank (not shown) may be included betweenthe reaction zone 101 and distillation zone 102 for temporarily storingthe liquid component from line 115, for example from 1 to 24 hours,optionally at a temperature of about 21° C., and corresponding to anethyl acetate formation of from 0.01 wt. % to 1.0 wt. % respectively. Inaddition, the rate at which the non-catalyzed reaction occurs mayincrease as the temperature of the crude ethanol product is increased.For example, as the temperature of the crude ethanol product in line 115increases from 4° C. to 21° C., the rate of ethyl acetate formation mayincrease from about 0.01 wt. % per hour to about 0.005 wt. % per hour.Thus, in one embodiment, the temperature of liquid components in line115 or in the optional holding tank is maintained at a temperature lessthan 21° C., e.g., less than 4° C. or less than −10° C.

In addition, it has now been discovered that the above-describedequilibrium reaction may also favor ethanol formation in the top regionof first column 107.

The distillate, e.g., overhead stream, of column 107 optionally iscondensed and refluxed as shown in FIG. 1, preferably, at a reflux ratioof 1:5 to 10:1. The distillate in line 117 preferably comprises ethanol,ethyl acetate, and water, along with other impurities, which may bedifficult to separate due to the formation of binary and tertiaryazeotropes.

The first distillate in line 117 is introduced to the second column 108,also referred to as the “light ends column,” preferably in the middlepart of column 108, e.g., middle half or middle third. As one example,when a 25 tray column is utilized in a column without water extraction,line 117 is introduced at tray 17. In one embodiment, the second column108 may be an extractive distillation column. In such embodiments, anextraction agent, such as water, may be added to second column 108. Ifthe extraction agent comprises water, it may be obtained from anexternal source or from an internal return/recycle line from one or moreof the other columns.

Second column 108 may be a tray column or packed column. In oneembodiment, second column 108 is a tray column having from 5 to 70trays, e.g., from 15 to 50 trays or from 20 to 45 trays.

Although the temperature and pressure of second column 108 may vary,when at atmospheric pressure the temperature of the second residueexiting in line 118 from second column 108 preferably is from 60° C. to90° C., e.g., from 70° C. to 90° C. or from 80° C. The temperature ofthe second distillate exiting in line 120 from second column 108preferably is from 50° C. to 90° C., e.g., from 60° C. to 80° C. or from60° C. to 70° C. Column 108 may operate at atmospheric pressure. Inother embodiments, the pressure of second column 108 may range from 0.1kPa to 510 kPa, e.g., from 1 kPa to 475 kPa or from 1 kPa to 375 kPa.Exemplary components for the distillate and residue compositions forsecond column 108 are provided in Table 4 below. It should be understoodthat the distillate and residue may also contain other components, notlisted, such as components in the feed.

TABLE 4 SECOND COLUMN Conc. (wt. %) Conc. (wt. %) Conc. (wt. %)Distillate Ethyl Acetate 10 to 90 25 to 90 50 to 90 Acetaldehyde  1 to25  1 to 15 1 to 8 Water  1 to 25  1 to 20  4 to 16 Ethanol <30 0.001 to15   0.01 to 5   Acetal <5 0.001 to 2    0.01 to 1   Residue Water 30 to70 30 to 60 30 to 50 Ethanol 20 to 75 30 to 70 40 to 70 Ethyl Acetate <30.001 to 2    0.001 to 0.5  Acetic Acid <0.5 0.001 to 0.3  0.001 to 0.2 

The weight ratio of ethanol in the second residue to ethanol in thesecond distillate preferably is at least 3:1, e.g., at least 6:1, atleast 8:1, at least 10:1 or at least 15:1. The weight ratio of ethylacetate in the second residue to ethyl acetate in the second distillatepreferably is less than 0.4:1, e.g., less than 0.2:1 or less than 0.1:1.In embodiments that use an extractive column with water as an extractionagent as the second column 108, the weight ratio of ethyl acetate in thesecond residue to ethyl acetate in the second distillate approacheszero.

As shown, the second residue from the bottom of second column 108, whichcomprises ethanol and water, is fed via line 118 to third column 109,also referred to as the “product column.” More preferably, the secondresidue in line 118 is introduced in the lower part of third column 109,e.g., lower half or lower third. Third column 109 recovers ethanol,which preferably is substantially pure other than the azeotropic watercontent, as the distillate in line 119. The distillate of third column109 preferably is refluxed as shown in FIG. 1, for example, at a refluxratio of from 1:10 to 10:1, e.g., from 1:3 to 3:1 or from 1:2 to 2:1.The third residue in line 121, which preferably comprises primarilywater, preferably is removed from the system 100 or may be partiallyreturned to any portion of the system 100. Third column 109 ispreferably a tray column as described above and preferably operates atatmospheric pressure. The temperature of the third distillate exiting inline 119 from third column 109 preferably is from 60° C. to 110° C.,e.g., from 70° C. to 100° C. or from 75° C. to 95° C. The temperature ofthe third residue exiting from third column 109 preferably is from 70°C. to 115° C., e.g., from 80° C. to 110° C. or from 85° C. to 105° C.,when the column is operated at atmospheric pressure. Exemplarycomponents of the distillate and residue compositions for third column109 are provided in Table 5 below. It should be understood that thedistillate and residue may also contain other components, not listed,such as components in the feed.

TABLE 5 THIRD COLUMN Conc. (wt. %) Conc. (wt. %) Conc. (wt. %)Distillate Ethanol 75 to 96   80 to 96  85 to 96 Water <12  1 to 9  3 to8 Acetic Acid <1 0.001 to 0.1 0.005 to 0.01 Ethyl Acetate <5 0.001 to 4 0.01 to 3  Residue Water 75 to 100   80 to 100  90 to 100 Ethanol <0.80.001 to 0.5 0.005 to 0.05 Ethyl Acetate <1 0.001 to 0.5 0.005 to 0.2 Acetic Acid <2 0.001 to 0.5 0.005 to 0.2 

The ethanol composition may comprise the impurities discussed above. Theethanol composition, in some embodiments, may further comprise othercompounds that result from the reaction or separation processes. Theseother compounds may be carried through the distillation process from thefeed or crude reaction product may generally remain in the thirddistillate in small amounts. For example, the other compounds may bepresent in amounts less 0.1 wt. %, based on the total weight of thethird distillate composition, e.g., less than 0.05 wt. % or less than0.02 wt. %. In one embodiment, one or more side streams may removeimpurities from any of the columns 107, 108 and/or 109 in the system100. Preferably at least one side stream is used to remove impuritiesfrom the third column 109. The impurities may be purged and/or retainedwithin the system 100.

The third distillate in line 119 may be further purified, as describedin more detail below, to form an anhydrous ethanol product stream, i.e.,“finished anhydrous ethanol,” using one or more additional separationsystems, such as, for example, distillation columns (e.g., a finishingcolumn) or molecular sieves.

Returning to second column 108, the second distillate preferably isrefluxed as shown in FIG. 1, for example, at a reflux ratio of from 1:10to 10:1, e.g., from 1:5 to 5:1 or from 1:3 to 3:1. The second distillatemay be fed via line 120 to fourth column 123, also referred to as the“acetaldehyde removal column.” In fourth column 123 the seconddistillate is separated into a fourth distillate, which comprisesacetaldehyde, in line 124 and a fourth residue, which comprises ethylacetate, in line 125. The fourth distillate preferably is refluxed at areflux ratio of from 1:20 to 20:1, e.g., from 1:15 to 15:1 or from 1:10to 10:1, and a portion of the fourth distillate is returned to thereaction zone 101 as shown by line 124. For example, the fourthdistillate may be combined with the acetic acid feed, added to thevaporizer 110, or added directly to the reactor 103. As shown, thefourth distillate is co-fed with the acetic acid in feed line 105 tovaporizer 110. Without being bound by theory, since acetaldehyde may behydrogenated to form ethanol, the recycling of a stream that containsacetaldehyde to the reaction zone increases the yield of ethanol anddecreases byproduct and waste generation. In another embodiment (notshown in the figure), the acetaldehyde may be collected and utilized,with or without further purification, to make useful products includingbut not limited to n-butanol, 1,3-butanediol, and/or crotonaldehyde andderivatives.

The fourth residue of fourth column 123 may be purged via line 125. Thefourth residue primarily comprises ethyl acetate and ethanol, which maybe suitable for use as a solvent mixture or in the production of esters.In one preferred embodiment, the acetaldehyde is removed from the seconddistillate in fourth column 123 such that no detectable amount ofacetaldehyde is present in the residue of column 123.

Fourth column 123 is preferably a tray column as described above andpreferably operates above atmospheric pressure. In one embodiment, thepressure is from 120 kPa to 5,000 kPa, e.g., from 200 kPa to 4,500 kPa,or from 400 kPa to 3,000 kPa. In a preferred embodiment the fourthcolumn 123 may operate at a pressure that is higher than the pressure ofthe other columns.

The temperature of the fourth distillate exiting in line 124 from fourthcolumn 123 preferably is from 60° C. to 110° C., e.g., from 70° C. to100° C. or from 75° C. to 95° C. The temperature of the residue exitingfrom fourth column 125 preferably is from 70° C. to 115° C., e.g., from80° C. to 110° C. or from 85° C. to 110° C. Exemplary components of thedistillate and residue compositions for fourth column 123 are providedin Table 6 below. It should be understood that the distillate andresidue may also contain other components, not listed, such ascomponents in the feed.

TABLE 6 FOURTH COLUMN Conc. (wt. %) Conc. (wt. %) Conc. (wt. %)Distillate Acetaldehyde 2 to 80    2 to 50 5 to 40 Ethyl Acetate <90  30 to 80 40 to 75  Ethanol <30 0.001 to 25 0.01 to 20   Water <250.001 to 20 0.01 to 15   Residue Ethyl Acetate 40 to 100    50 to 100 60to 100 Ethanol <40 0.001 to 30 0 to 15 Water <25 0.001 to 20 2 to 15Acetaldehyde <1  0.001 to 0.5 Not detectable Acetal <3 0.001 to 2  0.01to 1   

Although one reactor and one flasher are shown in FIG. 1, additionalreactors and/or components may be included in various optionalembodiments of the present invention. FIG. 2 represents a hydrogenationsystem 100′ that comprises dual reactors 103, 103′, dual flashers 106,106′, heat exchanger 130, and pre-heater 131. In this embodiment, aceticacid in line 105, along with the recycled acetic acid in line 116 andrecycled acetaldehyde from line 124, are heated in a heat exchanger 130and sent to vaporizer 110 via line 132. The temperature of the contentsof line 132 preferably is from 30° C. to 150° C., e.g., from 50° C. to130° C. or from 75° C. to 120° C. Hydrogen is fed via line 104 tovaporizer 110, which forms vaporized stream 111. Vaporized stream 111passes through pre-heater 131, which further heats stream 111 to atemperature of preferably from 200° C. to 300° C., e.g., from 210° C. to275° C. or from 220° C. to 260° C. The heated stream is then fed tofirst reactor 103. In order to control the reaction exotherm, the crudereaction mixture is removed from first reactor 103 via line 133 andcooled before being fed to a second reactor 103′, such that thetemperature of the reactants and products in contact with the catalystis maintained at or below 310° C. in order to minimize the formation ofundesired byproducts including methane, ethane, carbon dioxide, and/orcarbon monoxide. Additionally, above about 320° C. corrosion can becomesevere necessitating the use of exotic and expensive alloy materials.The temperature of the contents in line 133 after cooling preferably isfrom 200° C. to 300° C., e.g., from 210° C. to 275° C. or from 220° C.to 260° C. The reactors 103 and 103′ may be the same size andconfiguration or they may be of different size and configuration. Eachreactor preferably contains the same type of catalyst, althoughadditional and/or different catalysts may be used for each reactor. Asan example, the catalysts mentioned above may be utilized. Also,mixtures of catalysts, mixtures of catalysts and inert materials, and/orcatalysts with differing active metal concentrations may be utilized.For example, the catalyst may include the same types of metal in varyingmetal ratios. A crude ethanol product is withdrawn, preferablycontinuously, from reactor 103′ via line 112 and passes as a heatingmedium through heat exchanger 130 before being condensed and fed tofirst flasher 106. Thus, heat from the crude ethanol productadvantageously may be employed to preheat the acetic acid feed prior toits introduction into vaporizer 110. Conversely, the acetic acid feedmay be used as a cooling medium to cool the crude ethanol product priorto its introduction to first flasher 106. The vapor stream exiting thefirst flasher comprises hydrogen and hydrocarbons, which may be purgedand/or returned to reaction zone 101 via line 113. As shown in FIG. 2,at least a portion of the recycled vapor stream passes throughcompressor 114 and is co-fed with the hydrogen (or combined withhydrogen and then co-fed) to vaporizer 110.

The remaining liquid in flasher 106 is withdrawn via line 134 and fed toa second flasher 106′ to remove any residual vapor that is dissolved inthe liquid. Second flasher 106′ may operate at a lower temperatureand/or pressure than the first flasher 106. In one embodiment, thetemperature of second flasher 106′ preferably is from 20° C. to 100° C.,e.g., from 30° C. to 85° C. or from 40° C. to 70° C. In one embodiment,the temperature of second flasher 106′ preferably is at least 50° C.lower than first flasher 106, e.g., at least 75° C. lower or at least100° C. lower. The pressure of second flasher 106′ preferably is from0.1 kPa to 1000 kPa, e.g., from 0.1 kPa to 500 kPa or from 0.1 kPa to100 kPa. In one embodiment, the pressure of second flasher 106′preferably is at least 50 kPa lower than first flasher 106, e.g., atleast 100 kPa lower or at least 200 kPa lower. The vapor stream 135exiting the second flasher may comprise hydrogen and hydrocarbons, whichmay be purged and/or returned to the reaction zone in a manner similarto that of the first flasher 106. The remaining liquid in flasher 106′is withdrawn and pumped via line 115 to the side of the first column(not shown in FIG. 2) and is further purified to form an ethanol productstream, i.e., “finished ethanol,” as described, for example, inconnection with FIG. 1.

Finished Ethanol Composition

The finished ethanol compositions obtained by the processes of thepresent invention preferably comprises ethanol, water and minor amountsof isopropanol. As indicated above, preferably, the ethanol compositionis primarily ethanol and contains from 92 wt. % to 96 wt. % ethanol,e.g., from 93 wt. % to 96 wt. %, or from 95 wt. % to 96 wt. %. Inaddition, the amount of isopropanol in the ethanol composition rangesfrom 95 wppm to 1,000 wppm, e.g., from 110 wppm to 800 wppm, or from 110wppm to 400 wppm.

In another embodiment, the ethanol composition comprises less than 270wppm n-propanol and isopropanol, combined, e.g., less than 200 wppm. Interms of ranges, the ethanol composition comprises from 95 wppm to 270wppm n-propanol and isopropanol, combined, e.g., from 100 wppm to 250wppm, or from 120 wppm to 200 wppm. In preferred embodiments, theethanol compositions the total amount of isopropanol and n-propanol isless than 1,000 wppm, generally, e.g., less than 400 wppm or less than200 wppm.

In another embodiment, the ethanol composition comprises ethanol,isopropanol, and a low amount of alcohols other than ethanol andisopropanol, e.g., methanol, n-propanol, and C₄₊ alcohols. In oneembodiment, the ethanol composition comprises less than 350 wppmalcohols other than ethanol and isopropanol, e.g., less than 300 wppm orless than 275 wppm. In terms of ranges, the composition may comprisealcohols other than ethanol and isopropanol in amounts ranging from 1wppm to 350 wppm, e.g., 100 wppm to 325 wppm.

In addition, the ethanol compositions may comprise small amounts ofvarious organic impurities. Examples of these impurities includeacetaldehyde, acetic acid, diethyl acetal, ethyl acetate, n-propanol,methanol, butanol, 2-butanol, isobutanol, isoamyl alcohol, amyl alcohol,benzene and mixtures thereof. In a preferred embodiment, the inventiveethanol composition comprises low amounts of the organic impurities,e.g., less than 1 wt. % of organic impurities, less than 0.75 wt. %, orless than 0.5 wt. %. In another embodiment, the inventive ethanolcomposition comprises low amounts, if any, C₅ alcohols. For example, theethanol composition may comprise less than 0.005 wt. % C₅ alcohols,e.g., less than 0.001 wt. % or less than 0.0005 wt. %. In oneembodiment, the ethanol composition comprises from 50 wppm to 1.5 wt. %branched alcohols, e.g., from 100 wppm to 1 wt. %. In one embodiment,these branched alcohols do not include isopropanol. Exemplary weightpercentages for individual components are provided in Table 7.

TABLE 7 FINISHED ETHANOL COMPOSITIONS Component Conc. (wt. %) Conc. (wt.%) Conc. (wt. %) Ethanol 92 to 96 93 to 96 95 to 96 Water <8 <5 <2Acetic Acid <1 <0.1 <0.01 Ethyl Acetate <2 <0.5 <0.05 Acetone <0.05<0.01 <0.005 Isopropanol 0.0095 to 0.1   0.01 to 0.08 0.011 to 0.04 n-propanol <0.5 <0.1 <0.05 C₄ alcohols <0.01 <0.005 <0.003 C₅ alcohols<0.003 <0.0015 <0.0005 C₂₊ alcohols <0.75 <0.5 <0.1 Acetaldehyde <0.001<0.0005 <0.0002 Diethyl acetal <0.001 <0.0005 <0.0002 Methanol <0.005<0.004 0 Butanol <0.002 <0.0001 0 2-Butanol <0.008 <0.0008 0 Isobutanol<0.02 <0.003 0 Isoamyl alcohol <0.02 <0.0009 0 Amyl alcohol <0.02<0.0004 0

In other embodiments, the ethanol composition comprises very low amountsof metals, if any, e.g., the inventive ethanol composition comprisessubstantially no metals. For example, the inventive ethanol composition,in one embodiment, comprises less than 10 wppm copper, e.g., less than 1wppm, less than 0.1 wppm, or less than 0.05 wppm. In one embodiment, theethanol composition comprise substantially no copper, preferably theethanol composition comprises no copper. In one embodiment, theinventive ethanol composition comprises substantially no heavy metals.

In one embodiment, the ethanol composition comprises very low amounts ofinorganics. For example, the ethanol composition may comprise less than20 mg/liter of chlorine/chloride, e.g., less than 10 mg/liter, less than8 mg/liter or less than 5 mg/liter. In terms of parts per million, theethanol composition may comprise less than 40 wppm chlorine/chloride,e.g., less than 20 wppm or less than 10 wppm. In one embodiment, theethanol composition comprise substantially no chlorine, preferably theethanol composition comprises no chlorine.

In one embodiment, the ethanol composition comprises less than 50 wppmsulfur, e.g., less than 30 wppm, less than 10 wppm, less than 7 wppm,less than 5 wppm, or less than 3 wppm. In one embodiment, the ethanolcomposition comprise substantially no sulfur, preferably the ethanolcomposition comprises no sulfur. In one embodiment, the ethanolcomposition may comprise less than 10 wppm of sulfate, e.g., less than 4wppm, less than 3 wppm, less than 2 wppm, or less than 1 wppm. In oneembodiment, the ethanol composition comprise substantially no sulfates,preferably the ethanol composition comprises no sulfates.

In one embodiment, the ethanol composition comprises less than 2mg/liter of phosphorus, e.g., less than 1 mg/liter, less than 0.5mg/liter, less than 0.3 mg/liter, less than 0.2 mg/liter, or less than0.1 mg/liter. In one embodiment, the ethanol composition comprisesubstantially no phosphorus, preferably the ethanol compositioncomprises no phosphorus.

In one embodiment, the ethanol composition has a pHe ranging from 6.0 to9.5, e.g., from 6.5 to 9.0. In one embodiment, the ethanol compositionhas a total acidity, as acetic acid, is less than 0.01 wppm, e.g., lessthan 0.007 wppm. In one embodiment, the ethanol composition has a totalacidity, as acetic acid, is less than 65 mg/liter, e.g., less than 56mg/liter or less than 30 mg/liter.

In another embodiment, the ethanol composition comprises at least one insitu denaturant, e.g., a denaturant that is co-produced with theethanol. In these cases, the ethanol composition may be considered a“denatured ethanol composition.” Preferably, the denatured ethanolcomposition comprises no denaturants that are not prepared in situ viathe hydrogenation reaction. In one embodiment, the denatured ethanolcomposition comprises substantially no non-in situ denaturants. Becausethe denaturant is provided via the synthesis reaction, the denaturedethanol composition, as synthesized, beneficially requires no additional(outside) denaturants to form the denatured ethanol composition. As aresult, the denatured ethanol composition, as synthesized, is suitablefor commercial uses, e.g., is suitable for transportation as a denaturedethanol composition without further additions or processing.

Any of the component, percentage, or physical/chemical properties thatare discussed herein are applicable to any of the contemplated ethanolcompositions embodied herein.

The finished ethanol compositions disclosed herein are suitable for usein a variety of applications including fuels. In fuels applications, thefinished ethanol composition is blended with allowable denaturant toform the inventive denatured fuel ethanol compositions disclosed herein.The denatured fuel ethanol compositions so produced may subsequently beblended with gasoline or diesel fuel, for example, at a terminal loadingrack, for use in motor vehicles, such as automobiles, boats, trucks,marine vessels, locomotives and small piston engine aircrafts.

In the U.S., to conform to current regulations, the finished ethanolcompositions are blended with at least 1.96 vol. % of an allowable fueldenaturant. The maximum conforming amount of allowable fuel denaturantis currently 5 vol. %. As indicated above, allowable denaturants arelimited to natural gasoline, gasoline blendstocks and unleaded gasoline,pursuant to ASTM D4806. Suitable blendstocks include, but are notlimited to, alkylate streams, catalytically cracked gasoline streams(e.g., cracked naphtha); aromatic saturated gasoline streams, lightstraight run gasoline streams, heavy straight run gasoline streams,dehexanizer bottoms streams, dehexanizer overheads streams, hydrocrackertopper light naphtha, reformate, toluene and butane streams.

In one embodiment, the inventive ethanol composition is component of afuel composition. As one example, the fuel composition may comprise afuel component and the inventive ethanol, which may compriseisopropanol, e.g., in situ-formed isopropanol, in the amounts discussedherein. In some embodiments the fuel composition comprises non-insitu-formed alcohols, e.g., outside alcohols are added to the fuelcomposition. In one embodiment, the fuel composition comprises both insitu-formed isopropanol and non-in situ-formed isopropanol, e.g.,outside isopropanol. Conventional ethanol compositions do not comprisein situ formed isopropanol in the amounts disclosed herein.

Anhydrous Ethanol Production

Reference is now made to FIGS. 4A and 4B. Should it be required to meetthe performance specifications for denatured fuel ethanol, such as thoseof ASTM 4806-11, or other local requirements, the third distillate inline 119 may be further processed to substantially remove watertherefrom. The further processing results in the formation of ananhydrous ethanol product stream, e.g., anhydrous ethanol composition.In one embodiment, the further processing employs one or more separationunits, e.g., dehydrators. Examples of suitable dehydrators include anextractive distillation column 122 (as shown in FIG. 4A); a molecularsieve unit 124 (as shown in FIG. 4B); and/or a desiccant (not shown).For example, useful dehydration methods and/or units include thosediscussed in U.S. Pat. Nos. 4,465,875; 4,559,109; 4,654,123; and6,375,807. The entireties of these patents are hereby incorporated byreference.

Typically, the water and the ethanol in the third distillate form awater/ethanol azeotrope. In one embodiment, the dehydrators of thepresent invention remove the water from the water/ethanol azeotrope inthe third distillate. For example, the dehydration may remove at least50 wt. % of the water from the third distillate, e.g., at least 75 wt.%, at least 90 wt. %, at least 95 wt. %, or at least 99 wt. %. In termsof ranges, the dehydration removes from 50 wt. % to 100 wt. % of thewater from the third distillate, e.g., from 75 wt. % to 99.9999 wt. %,from 90 wt. % to 99.999 wt. %, from 90 wt. % to 99.99 wt. %, from 90 wt.% to 99.9 wt. %, or from 90 wt. % to 99.5 wt. %. The removal of thiswater from the third distillate results in the formation of theanhydrous ethanol composition.

Water-containing stream 128 exiting the dehydrator(s) comprisesprimarily water, e.g., at least 50 wt. % water, e.g., at least 75 wt. %,at least 90 wt. %, at least 95 wt. %, or at least 99 wt. %, andpreferably is removed from system 100. In one embodiment, the fourthresidue 128 may be partially returned to any portion of system 100. In apreferred embodiment, the water may be utilized as an extraction agentin any one of the columns, e.g., second column 108.

In FIG. 4A, the distillate from third column 109, which comprisesethanol/water azeotrope, may be fed, e.g., via line 119, to fourthcolumn 122, also referred to as the “finishing column.” Fourth column122 further separates, e.g., distills, water from the water/ethanolazeotrope in the third distillate. As a result, fourth column 122recovers ethanol that has been further dehydrated as the fourthdistillate in line 126.

Preferably, fourth column 122 is an extractive distillation column thatemploys an extraction agent and preferably operates at atmosphericpressure. Extractive distillation is a vapor-liquid separation process,which uses an additional component to increase the relative volatilityof the components to be separated. In extractive distillation, aselective high boiling solvent is utilized to alter the activitycoefficients and, hence, increase the separation factor of thecomponents. The additional component may be a liquid solvent, an ionicliquid, a dissolved salt, a mixture of volatile liquid solvent anddissolved salt, or hyperbranched polymer.

Fourth column 122 preferably comprises from 1 to 150 trays, e.g., from10 to 100 or from 20 to 70 trays. As indicated above, the trays may besieve trays, fixed valve trays, movable valve trays, or any othersuitable design known in the art. Exemplary extraction agents mayinclude, but are not limited to glycols, glycerol, gasoline, and hexane.The third distillate in line 119 may be introduced to fourth column 122at any level. Preferably, line 119 is introduced into the fourth column122 in the middle part of fourth column 122, e.g., the middle half ormiddle third.

In one embodiment, as shown in FIG. 4B, the distillate from third column109 is fed to a molecular sieve unit 124 comprising molecular sieves. Inthese embodiments, the molecular sieves separate additional water fromthe third distillate in line 119. In some embodiments, molecular sieveunit 124 may be used in place of or in conjunction with the finishingcolumn. Generally speaking, the molecular sieves may be configured in amolecular sieve bed (not shown). In one embodiment, the molecular sievesare selected to remove one or more impurities that may exist in thethird distillate. The selection criteria may include, for example, poresize and volume characteristics. In one embodiment, the molecular sievematerial is selected to remove water, acetic acid, and/or ethyl acetatefrom the third distillate to form the anhydrous ethanol composition.Suitable molecular sieves include, for example, zeolites and molecularsieves 3A, 4A and 5A (commercially available from Aldrich). In anotherembodiment, an inorganic adsorbents such as lithium chloride, silicagel, activated alumina, and/or bio-based adsorbents such as corn grits,may be utilized. In a preferred embodiment, molecular sieve unit 124removes water from the third distillate in the amounts discussed above.

In addition, other separation units, e.g., dehydrating units, such asdesiccant systems and/or membrane systems, may be used, either in placeof or in conjunction with the finishing column and/or the molecularsieve unit discussed above. If multiple dehydrating units are utilized,the dehydrating units, being of the same or of different type, may beutilized in any configuration. Preferably, an extractive distillationcolumn and a membrane system are utilized with one another. Optionally,the molecular sieves are employed in a bed within the finishing column,e.g., at the upper portion thereof.

Other exemplary dehydration processes include azeotropic distillationand membrane separation. In azeotropic distillation, a volatilecomponent, often referred to as an entrainer, is added to the componentsto be separated. The addition of the entrainer forms an azeotrope withthe components, thus changing the relative volatilities thereof. As aresult, the separation factors (activity coefficients) of the componentsare improved. The azeotropic distillation system, in one embodiment,comprises one or more distillation columns, e.g., two or more or threeor more.

Membrane separation, e.g., membrane pervaporation, may also be aneffective and energy-saving process for separating azeotropic mixtures.Generally speaking, pervaporation is based on the solution-diffusionmechanism, which relies on the gradient of the chemical potentialbetween the feed and the permeate sides of the membrane. The membranes,in one embodiment, may be hydrophilic or hydrophobic. Preferably, themembranes are hydrophilic or water permselective due to the smallermolecular size of water. In other embodiments, the membranes arehydrophobic or ethanol permselective. Typically, there are threecategories of membranes that may be used—inorganic, polymeric, andcomposite membrane.

Anhydrous Ethanol Composition

The anhydrous ethanol compositions beneficially comprise ethanol and, ifany, a small amount of water preferably formed via the inventive aceticacid hydrogenation and separation steps. In one embodiment, the term“anhydrous ethanol composition,” as used herein, means a substantiallyanhydrous ethanol composition. For example a substantially anhydrousethanol composition may have a water content of less than 1 wt. % water,e.g., less than 0.5 wt. %, less than 0.1 wt. %, less than 0.01 wt. %,less than 0.001 wt. %, or less than 0.0001 wt. %, based on the totalweight of the substantially anhydrous ethanol composition. Table 8provides exemplary ranges for the water concentration in the anhydrousethanol compositions. Although Table 8 indicated that water ispreferably present in a small amount, in other embodiments, theanhydrous ethanol composition may be completely anhydrous, e.g.,containing no detectable water. In these cases conventional waterdetection methods employed in the industry may be utilized to measurewater content or lack thereof. Preferably, the anhydrous ethanolcomposition comprises at least 95 wt. % ethanol, e.g., at least 95 wt.%, at least 99 wt. %, at least 99.9 wt. %, or at least 99.99 wt. %.Table 6 provides exemplary ranges for the ethanol concentration in theanhydrous ethanol compositions.

In addition to the ethanol and, if any, a small amount of water, theanhydrous ethanol composition may also comprise only trace amounts ofother impurities such as acetic acid; C₃ alcohols, e.g., n-propanol;and/or C₄-C₅ alcohols. Exemplary compositional ranges for the ethanol,the water, and various impurities that may be present in small amounts,if at all, are provided below in Table 8.

TABLE 8 ANHYDROUS ETHANOL COMPOSITIONS Component Conc. (wt. %) Conc.(wt. %) Conc. (wt. %) Ethanol     95 to 100    95 to 99.99    99 to99.90 Water 0.0001 to 1 0.001 to 0.5 0.001 to 0.05 Acetic Acid <1 <0.1<0.01 Ethyl Acetate <2 <0.5 <0.05 Acetal <0.05 <0.01 <0.005 Acetone<0.05 <0.01 <0.005 Isopropanol <0.5 <0.1 <0.05 n-propanol <0.5 <0.1<0.05

In other embodiments, the ethanol composition comprises very low amountsof metals, if any, e.g., the inventive ethanol composition comprisessubstantially no metals. For example, the inventive ethanol composition,in one embodiment, comprises less than 10 wppm copper, e.g., less than 1wppm, less than 0.1 wppm, or less than 0.05 wppm. In one embodiment, theinventive ethanol composition comprises substantially no heavy metals.

In one embodiment, the ethanol composition comprises very low amounts ofinorganics. For example, the ethanol composition may comprise less than10 mg/liter of chlorine/chloride, e.g., less than 8 mg/liter or lessthan 5 mg/liter. In terms of parts per million, the ethanol compositionmay comprise less than 40 wppm chlorine/chloride, e.g., less than 20wppm or less than 10 wppm. In one embodiment, the ethanol compositioncomprises less than 30 wppm sulfur, e.g., less than 10 wppm, less than 7wppm, less than 5 wppm, or less than 3 wppm. For example, the ethanolcomposition may comprise less than 4 wppm of sulfate, e.g., less than 3wppm, less than 2 wppm, or less than 1 wppm. In one embodiment, theethanol composition comprises less than 0.5 mg/liter of phosphorus,e.g., less than 0.3 mg/liter, less than 0.2 mg/liter, or less than 0.1mg/liter.

The anhydrous ethanol compositions of the present invention preferablycontain very low amounts, e.g., less than 0.5 wt. %, of other alcohols,such as methanol, butanol, isobutanol, isoamyl alcohol and other C₄-C₂₀alcohols.

The anhydrous ethanol compositions of the embodiments of the presentinvention may be suitable for use in a variety of applications includingfuels. In fuels applications, the anhydrous ethanol composition may beblended with allowable denaturant, as described above, then subsequentlyblended, such as at a loading terminal rack, with gasoline or dieselfuel, for motor vehicles, such as automobiles, boats, trucks, marinevessels, locomotives and small piston engine aircrafts.

In the U.S., to conform to current regulations, the anhydrous ethanolcompositions are blended with at least 1.96 vol. % of an allowable fueldenaturant. The maximum conforming amount of allowable fuel denaturantis currently 5 vol. %. As indicated above, allowable denaturants arelimited to natural gasoline, gasoline blendstocks and unleaded gasoline,pursuant to ASTM D4806. Suitable blendstocks include, but are notlimited to, alkylate streams, catalytically cracked gasoline streams(e.g., cracked naphtha); aromatic saturated gasoline streams, lightstraight run gasoline streams, heavy straight run gasoline streams,dehexanizer bottoms streams, dehexanizer overheads streams, hydrocrackertopper light naphtha, reformate, toluene and butane streams.

The denatured fuel ethanol compositions produced in accordance with thepresent invention are capable of meeting the Standard Specification forDenatured Fuel Ethanol for Blending with Gasolines for Use as AutomotiveSpark Ignition Engine Fuel, ASTM D4806-11, the performance requirementsof which are presented in Table 9, below.

TABLE 9 PERFORMANCE REQUIREMENTS ASTM D4806-11 ASTM Test Limit MethodEthanol, volume %, min. 92.1  D5501 Methanol, volume %, max. 0.5 D5501Solvent-washed gum content, 5.0 D381 mg/100 mL, max. Water, volume %(mass %), max. 1.0 (1.26) E203 or E1064 Inorganic Chloride, mass ppm10.0 (8) D7319 or D7328 (mg/L), max. Copper, mg/kg, max 0.1 D1688Acidity (as acetic acid CH₃COOH) 0.007 (56) D1613 mass % (mg/L), max pHe6.5 to 9.0 D6423 Sulfur, mass ppm, max. 30.4  D2622, D3120, D5453 orD7039 Total sulfate, mass ppm, max. 1.0 (1.26) D7318, D7319 or D7328

In an embodiment, the fuel blended ethanol composition comprises verylow amounts of metals, if any, e.g., the fuel blended ethanolcomposition comprises substantially no metals. In another embodiment,the fuel blended ethanol composition comprises substantially no heavymetals. For example the fuel blended ethanol composition issubstantially free of lead, in one embodiment, comprises less than 20mg/l lead, e.g., less than 15 mg/l, less than 10 mg/l, or less than 5mg/l. In one embodiment, the fuel blended ethanol composition issubstantially free of manganese. For example, the fuel blended ethanolcomposition comprises less than 10 mg/l manganese, e.g., less than 6mg/l, less than 3mg/l, less than 1 mg/l. In one embodiment, the fuelblended ethanol composition is substantially free of cooper. Forexample, the fuel blended ethanol composition comprises less than 0.5mg/kg copper, or less than 0.3 mg/kg copper, or less than 0.1 mg/kgcopper. In one embodiment, the fuel blended ethanol composition issubstantially free of a combination of sodium and potassium. Forexample, the fuel blended ethanol composition comprises less than 10mg/kg a combination of sodium and potassium, e.g., less than 8 mg/kg,less than 5 mg/kg, or less than 2 mg/kg. In an embodiment, the fuelblended ethanol composition is substantially free of a combination ofcalcium and magnesium. For example, the fuel blended ethanol compositioncomprises less than 15 mg/kg of a combination of calcium and magnesium,e.g., less than 10 mg/kg, less than 5 mg/kg, or less than 2 mg/kg. Inanother embodiment, the fuel blended ethanol composition issubstantially free of aluminum and silicon. For example, the fuelblended ethanol composition comprises less than 60 mg/kg of acombination of aluminum and silicon, e.g., less than 50 mg/kg, less than25 mg/kg, less than 10 mg/kg, or less than 5 mg/kg. In anotherembodiment, the fuel blended ethanol composition is substantially freeof sodium. For example, the fuel blended ethanol composition comprisesless than 150 mg/kg sodium, e.g., less than 100 mg/kg, less than 50mg/kg, or less than 10 mg/kg. In one embodiment, the fuel blendedethanol composition is substantially free of vanadium. For example, thefuel blended ethanol composition comprises less than 400 mg/kg vanadium,e.g., less than 350 mg/kg, less than 200 mg/kg or less than 150 mg/kg.In another embodiment, the fuel blended ethanol composition issubstantially free of calcium. For example, the fuel blended ethanolcomposition comprises less than 50 mg/kg calcium, e.g., less than 30mg/kg, less than 15 mg/kg or less than 10 mg/kg. In another embodiment,the fuel blended ethanol composition is substantially free of zinc. Forexample, the fuel blended ethanol composition comprises less than 25mg/kg zinc, e.g., less than 15 mg/kg, or less than 10 mg/kg.

In order that the invention disclosed herein may be more efficientlyunderstood, a non-limiting example is provided below. The followingexamples describe various embodiments of the inventive ethanolcomposition.

EXAMPLES Example 1

Several ethanol compositions were prepared using the hydrogenationprocess described above as well as the separation process. Crude ethanolproducts comprising ethanol, acetic acid, water and ethyl acetate wereproduced by reacting a vaporized feed comprising 95.2 wt. % acetic acidand 4.6 wt. % water with hydrogen in the presence of a catalystcomprising 1.6 wt. % platinum and 1 wt. % tin supported on 1/8 inchcalcium silicate modified silica extrudates at an average temperature of291° C., an outlet pressure of 2,063 KPa. Unreacted hydrogen wasrecycled back to the inlet of the reactor such that the total H₂/aceticacid molar ratio was 5.8 at a GHSV of 3,893 hr⁻¹. The crude ethanolproducts were purified using a separation scheme having distillationcolumns as shown in FIG. 1.

Table 10 shows compositional data for these ethanol compositions. Theterm “C₂₊ alcohols” as used herein relates to alcohols having more thantwo carbon atoms.

TABLE 10 FINISHED ETHANOL COMPOSITION RANGES Component Avg. Ethanol 92.7wt. % Water 7.4 wt. % Acetic Acid 14 wppm Ethyl Acetate 70 wppmIsopropanol 110 wppm n-propanol 160 wppm C₄ alcohols 21 wppm C₅ alcohols0 C₂₊ alcohols 291 wppm Acetaldehyde 5 wppm Diethyl acetal 1 wppmMethanol not detectable

Comparative Example A

Table 11 shows data for a comparative ethanol compositions prepared viafermentation of sugarcane.

TABLE 11 COMPARATIVE ETHANOL COMPOSITION RANGES Component Avg. Ethanol93.4 wt. % Water 6.6 wt. % Acetic Acid 11 wppm Ethyl Acetate 51 wppmIsopropanol 2 wppm n-propanol 238 wppm C₄ alcohols 35 wppm C₅ alcohols12 wppm C₂₊ alcohols 288 wppm Acetaldehyde 29 wppm Diethyl acetal 59wppm Methanol 51 wppm

Comparative Example B

Table 12 shows data for a comparative ethanol compositions prepared viafermentation of molasses.

TABLE 12 COMPARATIVE ETHANOL COMPOSITION RANGES Component Avg. Ethanol93.4 wt. % Water 6.5 wt. % Acetic Acid 10 wppm Ethyl Acetate —Isopropanol 17 wppm n-propanol 109 wppm C₄ alcohols 20 wppm C₅ alcohols11 wppm C₂₊ alcohols 156 wppm Acetaldehyde 18 wppm Diethyl acetal 55wppm Methanol 42 wppm

Comparative Example C

Table 13 shows data for a comparative ethanol compositions prepared viaFischer-Tropsch synthesis.

TABLE 13 COMPARATIVE ETHANOL COMPOSITION RANGES Component Avg. Ethanol93.1 wt. % Water 6.9 wt. % Acetic Acid 8 wppm Ethyl Acetate — C₄alcohols 17 wppm C₅ alcohols 5 wppm C₂₊ alcohols 261 wppm Isopropanol 10wppm n-propanol 121 wppm Higher alcohols 131 wppm Acetaldehyde 4 wppmDiethyl acetal 10 wppm Methanol 46 wppm

Surprisingly and unexpectedly, the amount of isopropanol in Example 1 ishigher than in Comparative Examples A-C. Also, the amount of methanol inExample 1 is, advantageously, not detectable. In contrast, the amount ofmethanol in Comparative Examples A-C is significantly higher, e.g., 42wppm to 51 wppm.

Example 2

Crude ethanol product samples were prepared via acetic acidhydrogenation as discussed above. The samples comprised ethanol, aceticacid, acetaldehyde, water, and ethyl acetate.

Each of the crude ethanol product samples was purified using first,second, and third columns as shown in FIG. 1A. In each case, the thirddistillate, yielded from the respective crude ethanol product sample,was analyzed. The average compositional values of the third distillateare provided in Table 14.

TABLE 14 Third Distillate Component (avg. wt. %) Ethanol 92.27 Water 7.7Ethyl Acetate 0.008 Acetaldehyde 0.0002 Acetic Acid 0.0001 Isopropanol0.0118 N-propanol 0.0127 Acetone 0 Acetal 0.0001

The third distillates, when dehydrated as discussed above, provide foranhydrous ethanol compositions having the average compositional valuesare provided in Table 15. As shown in Table 15, the anhydrous ethanolcompositions that may be formed via the inventive acetic acidhydrogenation and separation steps, comprise ethanol and, if any, asmall amount of water.

TABLE 15 Anhydrous Ethanol Compositions Component (avg. wt. %) Ethanol99.46 Water 0.50 Ethyl Acetate 0.009 Acetaldehyde 0.0002 Acetic Acid0.0001 Isopropanol 0.0127 N-propanol 0.0131 Acetone 0 Acetal 0.0001

While the invention has been described in detail, modifications withinthe spirit and scope of the invention will be readily apparent to thoseof skill in the art. In view of the foregoing discussion, relevantknowledge in the art and references discussed above in connection withthe Background and Detailed Description, the disclosures of which areall incorporated herein by reference. In addition, it should beunderstood that aspects of the invention and portions of variousembodiments and various features recited below and/or in the appendedclaims may be combined or interchanged either in whole or in part. Inthe foregoing descriptions of the various embodiments, those embodimentswhich refer to another embodiment may be appropriately combined withother embodiments as will be appreciated by one of skill in the art.Furthermore, those of ordinary skill in the art will appreciate that theforegoing description is by way of example only, and is not intended tolimit the invention.

We claim:
 1. A denatured fuel ethanol composition for blending with afuel, comprising: an ethanol composition comprising at least 92 wt. %ethanol, from 95 wppm to 850 wppm isopropanol; n-propanol; and at least1.96 vol. % fuel denaturant, wherein the weight ratio of isopropanol ton-propanol is at least 0.5:1.
 2. The denatured fuel ethanol compositionof claim 1, wherein the fuel denaturant is selected from naturalgasoline, gasoline blendstocks and unleaded gasoline.
 3. The denaturedfuel ethanol composition of claim 1, further comprising less than 1 vol.% water.
 4. The denatured fuel ethanol composition of claim 3, whereinthe weight ratio of isopropanol to water in the ethanol compositionranges from 1:80 to 1:1000.
 5. The denatured fuel ethanol composition ofclaim 1, further comprising one or more organic impurities selected fromthe group consisting of acetaldehyde, acetic acid, diethyl acetal, ethylacetate, butanol, 2-butanol, isobutanol, and mixtures thereof.
 6. Thedenatured fuel ethanol composition of claim 5, wherein the ethanolcomposition comprises less than 1 wt. % of the one or more organicimpurities.
 7. The denature fuel ethanol composition of claim 1, whereinthe ethanol composition further comprises less than 10 wppmacetaldehyde.
 8. The denature fuel ethanol composition of claim 1,wherein the ethanol composition further comprises less than 10 wppm ofdiethyl acetal.
 9. The denatured fuel ethanol composition of claim 1,wherein the ethanol composition further comprises less than 300 wppm C₄to C₅ alcohols.
 10. The denatured fuel ethanol composition of claim 1,wherein the ethanol composition further comprises from 95 wppm to 270wppm of n-propanol.
 11. The denatured fuel ethanol composition of claim1, wherein the ethanol composition comprises less than 1 wt % benzene.12. The denatured fuel ethanol composition of claim 1, wherein theethanol composition comprises less than 0.005 wt % methanol.
 13. Thedenatured fuel ethanol composition of claim 1, wherein the ethanolcomposition comprises no methanol.
 14. The denatured fuel ethanolcomposition of claim 1, wherein the ethanol composition comprises lessthan 0.005 wt % C₅ alcohols.
 15. The denatured fuel ethanol compositionof claim 1, wherein the ethanol composition is not fermentation derived.16. The denatured fuel ethanol composition of claim 1, wherein theethanol composition comprises less than 20 wppm chlorine.
 17. Thedenatured fuel ethanol composition of claim 1, wherein the ethanolcomposition comprises no chlorine.
 18. The denatured fuel ethanolcomposition of claim 1, wherein the ethanol composition comprises lessthan 40 wppm chlorine.
 19. The denatured fuel ethanol composition ofclaim 1, wherein the ethanol composition comprises less than 1 wppmcopper.
 20. The denatured fuel ethanol composition of claim 1 , whereinthe ethanol composition comprises no copper.
 21. The denatured fuelethanol composition of claim 1, wherein the ethanol compositioncomprises less than 10 wppm copper.
 22. The denatured fuel ethanolcomposition of claim 1, wherein the ethanol composition comprises lessthan 30 wppm sulfur.
 23. The denatured fuel ethanol composition of claim1, wherein the ethanol composition comprises no sulfur.
 24. Thedenatured fuel ethanol composition of claim 1, wherein the ethanolcomposition comprises less than 50 wppm sulfur.
 25. The denatured fuelethanol composition of claim 1, wherein the ethanol compositioncomprises less than 4 wppm sulfates.
 26. The denatured fuel ethanolcomposition of claim 1, wherein the ethanol composition comprises nosulfates.
 27. The denatured fuel ethanol composition of claim 1, whereinthe ethanol composition comprises less than 10 wppm sulfates.
 28. Thedenatured fuel ethanol composition of claim 1, wherein the ethanolcomposition comprises less than 0.5 milligrams per liter phosphorus. 29.The denatured fuel ethanol composition of claim 1, wherein the ethanolcomposition comprises no phosphorus.
 30. The denatured fuel ethanolcomposition of claim 1, wherein the ethanol composition comprises lessthan 2 milligrams per liter phosphorus.
 31. The denatured fuel ethanolcomposition of claim 1, wherein the fuel blended ethanol compositioncomprises less than 20 mg/l lead.
 32. The denatured fuel ethanolcomposition of claim 1, wherein the fuel blended ethanol compositioncomprises less than 15 mg/l lead.
 33. The denatured fuel ethanolcomposition of claim 1, wherein the fuel blended ethanol compositioncomprises less than 5 mg/l lead.
 34. The denatured fuel ethanolcomposition of claim 1, wherein the fuel blended ethanol compositioncomprises less than 10 mg/l manganese.
 35. The denatured fuel ethanolcomposition of claim 1, wherein the fuel blended ethanol compositioncomprises less than 1 mg/l manganese.
 36. The denatured fuel ethanolcomposition of claim 1 wherein the fuel blended ethanol compositionmetals comprises less than 20 mg/l heavy metals.
 37. The denatured fuelethanol composition of claim 1, wherein the fuel blended ethanolcomposition comprises less than 0.5 mg/kg copper.
 38. The denatured fuelethanol composition of claim 1, wherein the fuel blended ethanolcomposition comprises less than 0.1 mg/kg copper.
 39. The denatured fuelethanol composition of claim 1, wherein the fuel blended ethanolcomposition comprises less than 8 mg/kg of a combination of sodium andpotassium.
 40. The denatured fuel ethanol composition of claim 1,wherein the fuel blended ethanol composition comprises less than 5 mg/kgof a combination of sodium and potassium.
 41. The denatured fuel ethanolcomposition of claim 1, wherein the fuel blended ethanol compositioncomprises less than 10 mg/kg of a combination of calcium and magnesium.42. The denatured fuel ethanol composition of claim 1, wherein the fuelblended ethanol composition comprises less than 5 mg/kg of a combinationof calcium and magnesium.
 43. The denatured fuel ethanol composition ofclaim 1, wherein the fuel blended ethanol composition comprises lessthan 60 mg/kg of a combination of aluminum and silicon.
 44. Thedenatured fuel ethanol composition of claim 1, wherein the fuel blendedethanol composition comprises less than 25 mg/kg of a combination ofaluminum and silicon.
 45. The denatured fuel ethanol composition ofclaim 1, wherein the fuel blended ethanol composition comprises lessthan 150 mg/kg sodium.
 46. The denatured fuel ethanol composition ofclaim 1, wherein the fuel blended ethanol composition comprises lessthan 100 mg/kg sodium.
 47. The denatured fuel ethanol composition ofclaim 1, wherein the fuel blended ethanol composition comprises lessthan 400 mg/kg vanadium.
 48. The denatured fuel ethanol composition ofclaim 1, wherein the fuel blended ethanol composition comprises lessthan 350 mg/kg vanadium.
 49. The denatured fuel ethanol composition ofclaim 1, wherein the fuel blended ethanol composition comprises lessthan 50 mg/kg calcium.
 50. The denatured fuel ethanol composition ofclaim 1, wherein the fuel blended ethanol composition comprises lessthan 30 mg/kg calcium.
 51. The denatured fuel ethanol composition ofclaim 1, wherein the fuel blended ethanol composition comprises lessthan 25 mg/kg zinc.
 52. The denatured fuel ethanol composition of claim1, wherein the fuel blended ethanol composition comprises less than 15mg/kg zinc.
 53. The denatured fuel ethanol composition of claim 1,wherein the ethanol composition has a pH ranging from 6 to 9.5.
 54. Thedenatured fuel ethanol composition of claim 1, wherein the ethanolcomposition has a total acidity, as acetic acid, is less than 0.01 wppm.55. The denatured fuel ethanol composition of claim 1, wherein theethanol composition comprises less than 350 wppm alcohols other thanethanol.
 56. The denatured fuel ethanol composition of claim 1, whereinthe ethanol composition is derived from the hydrogenation of aceticacid.
 57. The denatured fuel ethanol composition of claim 56, whereinthe acetic acid is formed from methanol and carbon monoxide, whereineach of the methanol, the carbon monoxide, and hydrogen for thehydrogenating step is derived from syngas, and wherein the syngas isderived from a carbon source selected from the group consisting ofnatural gas, oil, petroleum, coal, biomass, and combinations thereof.58. The denatured fuel ethanol composition of claim 1, wherein the fuelfor blending with the denatured fuel ethanol composition is a gasoline.59. The denatured fuel ethanol composition of claim 1, wherein the fuelfor blending with the denatured fuel ethanol composition is a dieselfuel.
 60. A denatured fuel ethanol composition for blending with a fuel,comprising: an ethanol composition comprising at least 92 wt. % ethanol,at least two other alcohols selected from the group consisting ofisopropanol, butanol, 2-butanol, and isobutanol, provided that one ofthe at least two other alcohols is isopropanol and there is at least 95wppm isopropanol and acetaldehyde present in an amount less than 10wppm; and at least 1.96 vol. % fuel denaturant, wherein the ethanolcomposition comprises less than 0.005wt % methanol.
 61. The denaturedfuel ethanol composition of claim 60, wherein the at least two otheralcohols are present in the ethanol composition in an amount of lessthan 1 wt. %.
 62. The denatured fuel ethanol composition of claim 60,wherein the isopropanol is present in the ethanol composition in anamount of less than 850 wppm.
 63. The denatured fuel ethanol compositionof claim 60, further comprising less than 1 vol. % water.
 64. Thedenatured fuel ethanol composition of claim 60, wherein the at least twoother alcohols are in situ-formed alcohols.
 65. The denatured fuelethanol composition of claim 60, wherein the ethanol composition issynthesized via acetic acid hydrogenation and purification and whereinthe denatured ethanol composition, as synthesized, comprisessubstantially no non-in situ denaturants.
 66. The denatured fuel ethanolcomposition of claim 65, wherein the denatured ethanol composition, assynthesized, is suitable for commercial use.
 67. The denatured fuelethanol composition of claim 60, further comprising one or moreadditional alcohols that are not in situ-formed alcohols.
 68. Thedenatured fuel ethanol composition of claim 60, wherein the fuel forblending with the composition is a gasoline.
 69. The denatured fuelethanol composition of claim 60, wherein the fuel for blending with thecomposition is a diesel fuel.
 70. A denatured fuel ethanol compositionfor blending with a fuel, comprising: an ethanol composition comprisingat least 95 wt. % ethanol, at least 95 wppm isopropanol, and n-propanol,wherein the weight ratio of isopropanol to n-propanol is at least 0.5:1;and at least 1.96 vol. % fuel denaturant.
 71. The denatured fuel ethanolcomposition of claim 70, wherein the weight ratio of isopropanol ton-propanol present in the ethanol composition is at least 1:1.
 72. Thedenatured fuel ethanol composition of claim 70, wherein the isopropanolis present in the ethanol composition is in an amount of less than 1000wppm.
 73. The denatured fuel ethanol composition of claim 70, whereinthe n-propanol is present in the ethanol composition is in an amount ofless than 270 wppm.
 74. The denatured fuel ethanol composition of claim70, further comprising less than 1 vol. % water.
 75. The denatured fuelethanol composition of claim 70, wherein the isopropanol and then-propanol are in situ-formed alcohols.
 76. The denatured fuel ethanolcomposition of claim 75, wherein the ethanol composition is synthesizedvia acetic acid hydrogenation and purification and wherein the denaturedethanol composition, as formed, comprises substantially no non-in situdenaturants.
 77. The denatured fuel ethanol composition of claim 76,wherein the denatured ethanol composition, as formed, is suitable forcommercial use.
 78. The denatured fuel ethanol composition of claim 76,further comprising one or more additional alcohols that are not insitu-formed alcohols.
 79. The denatured fuel ethanol composition ofclaim 70, wherein the fuel for blending with the composition is agasoline.
 80. The denatured fuel ethanol composition of claim 70,wherein the fuel for blending with the composition is a diesel fuel.